The order of actions. The order of actions, rules, examples The order of calculation in expressions with powers, roots, logarithms and other functions

And when calculating the values of expressions, actions are performed in a certain order, in other words, you must observe order of actions.

In this article, we will figure out which actions should be performed first, and which ones after them. Let's start with the simplest cases, when the expression contains only numbers or variables connected by plus, minus, multiply and divide. Next, we will explain what order of execution of actions should be followed in expressions with brackets. Finally, consider the sequence in which actions are performed in expressions containing powers, roots, and other functions.

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First multiplication and division, then addition and subtraction

The school provides the following a rule that determines the order in which actions are performed in expressions without parentheses:

actions are performed in order from left to right,
where multiplication and division are performed first, and then addition and subtraction.

The stated rule is perceived quite naturally. Performing actions in order from left to right is explained by the fact that it is customary for us to keep records from left to right. And the fact that multiplication and division is performed before addition and subtraction is explained by the meaning that these actions carry in themselves.

Let's look at a few examples of the application of this rule. For examples, we will take the simplest numerical expressions so as not to be distracted by calculations, but to focus on the order in which actions are performed.

Example.

Follow steps 7−3+6 .

Solution.

The original expression does not contain parentheses, nor does it contain multiplication and division. Therefore, we should perform all actions in order from left to right, that is, first we subtract 3 from 7, we get 4, after which we add 6 to the resulting difference 4, we get 10.

Briefly, the solution can be written as follows: 7−3+6=4+6=10 .

Answer:

7−3+6=10 .

Example.

Indicate the order in which actions are performed in the expression 6:2·8:3 .

Solution.

To answer the question of the problem, let's turn to the rule that indicates the order in which actions are performed in expressions without brackets. The original expression contains only the operations of multiplication and division, and according to the rule, they must be performed in order from left to right.

Answer:

At first 6 divided by 2, this quotient is multiplied by 8, finally, the result is divided by 3.

Example.

Calculate the value of the expression 17−5·6:3−2+4:2 .

Solution.

First, let's determine in what order the actions in the original expression should be performed. It includes both multiplication and division and addition and subtraction. First, from left to right, you need to perform multiplication and division. So we multiply 5 by 6, we get 30, we divide this number by 3, we get 10. Now we divide 4 by 2, we get 2. We substitute the found value 10 instead of 5 6:3 in the original expression, and the value 2 instead of 4:2, we have 17−5 6:3−2+4:2=17−10−2+2.

There is no multiplication and division in the resulting expression, so it remains to perform the remaining actions in order from left to right: 17−10−2+2=7−2+2=5+2=7 .

Answer:

17−5 6:3−2+4:2=7 .

At first, in order not to confuse the order of performing actions when calculating the value of an expression, it is convenient to place numbers above the signs of actions corresponding to the order in which they are performed. For the previous example, it would look like this: .

The same order of operations - first multiplication and division, then addition and subtraction - should be followed when working with literal expressions.

Steps 1 and 2

In some textbooks on mathematics, there is a division of arithmetic operations into operations of the first and second steps. Let's deal with this.

Definition.

First step actions are called addition and subtraction, and multiplication and division are called second step actions.

In these terms, the rule from the previous paragraph, which determines the order in which actions are performed, will be written as follows: if the expression does not contain brackets, then in order from left to right, the actions of the second stage (multiplication and division) are performed first, then the actions of the first stage (addition and subtraction).

Order of execution of arithmetic operations in expressions with brackets

Expressions often contain parentheses to indicate the order in which the actions are to be performed. In this case a rule that specifies the order in which actions are performed in expressions with brackets, is formulated as follows: first, the actions in brackets are performed, while multiplication and division are also performed in order from left to right, then addition and subtraction.

So, expressions in brackets are considered as components of the original expression, and the order of actions already known to us is preserved in them. Consider the solutions of examples for greater clarity.

Example.

Do the given steps 5+(7−2 3) (6−4):2 .

Solution.

The expression contains brackets, so let's first perform the operations in the expressions enclosed in these brackets. Let's start with the expression 7−2 3 . In it, you must first perform the multiplication, and only then the subtraction, we have 7−2 3=7−6=1 . We pass to the second expression in brackets 6−4 . There is only one action here - subtraction, we perform it 6−4=2 .

We substitute the obtained values into the original expression: 5+(7−2 3)(6−4):2=5+1 2:2. In the resulting expression, first we perform multiplication and division from left to right, then subtraction, we get 5+1 2:2=5+2:2=5+1=6 . On this, all actions are completed, we adhered to the following order of their execution: 5+(7−2 3) (6−4):2 .

Let's write a short solution: 5+(7−2 3)(6−4):2=5+1 2:2=5+1=6.

Answer:

5+(7−2 3)(6−4):2=6 .

It happens that an expression contains brackets within brackets. You should not be afraid of this, you just need to consistently apply the voiced rule for performing actions in expressions with brackets. Let's show an example solution.

Example.

Perform the actions in the expression 4+(3+1+4·(2+3)) .

Solution.

This is an expression with brackets, which means that the execution of actions must begin with the expression in brackets, that is, with 3+1+4 (2+3) . This expression also contains parentheses, so you must first perform actions in them. Let's do this: 2+3=5 . Substituting the found value, we get 3+1+4 5 . In this expression, we first perform multiplication, then addition, we have 3+1+4 5=3+1+20=24 . The initial value, after substituting this value, takes the form 4+24 , and it remains only to complete the actions: 4+24=28 .

Answer:

4+(3+1+4 (2+3))=28 .

In general, when parentheses within parentheses are present in an expression, it is often convenient to start with the inner parentheses and work your way to the outer ones.

For example, let's say we need to perform operations in the expression (4+(4+(4−6:2))−1)−1 . First, we perform actions in internal brackets, since 4−6:2=4−3=1 , then after that the original expression will take the form (4+(4+1)−1)−1 . Again, we perform the action in the inner brackets, since 4+1=5 , then we arrive at the following expression (4+5−1)−1 . Again, we perform the actions in brackets: 4+5−1=8 , while we arrive at the difference 8−1 , which is equal to 7 .

To correctly evaluate expressions in which you need to perform more than one operation, you need to know the order in which arithmetic operations are performed. Arithmetic operations in the expression without brackets agreed to be performed in the following order:

If there is exponentiation in the expression, then this action is first performed in sequential order, that is, from left to right.
Then (if present in the expression), the operations of multiplication and division are performed in the order in which they appear.
The last (if present in the expression) operations of addition and subtraction are performed in the order in which they appear.

As an example, consider the following expression:

First you need to perform exponentiation (square the number 4 and cube the number 2):

3 16 - 8: 2 + 20

Then multiplication and division are performed (3 times 16 and 8 divided by 2):

And at the very end, subtraction and addition are performed (subtract 4 from 48 and add 20 to the result):

48 - 4 + 20 = 44 + 20 = 64

Steps 1 and 2

Arithmetic operations are divided into operations of the first and second stages. Addition and subtraction are called first step actions, multiplication and division - second step actions.

If the expression contains actions of only one stage and there are no brackets in it, then the actions are performed in the order they appear from left to right.

Example 1

15 + 17 - 20 + 8 - 12

Solution. This expression contains the actions of only one stage - the first (addition and subtraction). It is necessary to determine the order of actions and carry them out.

Answer: 42.

If the expression contains the actions of both stages, then the actions of the second stage are executed first, in their order (from left to right), and then the actions of the first stage.

Example. Calculate the value of an expression:

24:3 + 5 2 - 17

Solution. This expression contains four actions: two of the first stage and two of the second. Let's define the order of their execution: according to the rule, the first action will be division, the second - multiplication, the third - addition, and the fourth - subtraction.

Now let's start the calculation.

When we work with various expressions, including numbers, letters and variables, we have to perform a large number of arithmetic operations. When we do a transformation or calculate a value, it is very important to follow the correct order of these actions. In other words, arithmetic operations have their own special execution order.

In this article, we will tell you what actions should be done first and which after. First, let's look at a few simple expressions that contain only variables or numeric values, as well as division, multiplication, subtraction, and addition signs. Then we will take examples with brackets and consider in what order they should be evaluated. In the third part, we will give the correct order of transformations and calculations in those examples that include the signs of roots, powers, and other functions.

Definition 1

In the case of expressions without brackets, the order of actions is determined unambiguously:

All actions are performed from left to right.
First of all, we perform division and multiplication, and secondly, subtraction and addition.

The meaning of these rules is easy to understand. The traditional writing order from left to right determines the basic sequence of calculations, and the need to multiply or divide first is explained by the very essence of these operations.

Let's take a few tasks for clarity. We have used only the simplest numerical expressions so that all calculations can be done mentally. So you can quickly remember the desired order and quickly check the results.

Example 1

Condition: calculate how much 7 − 3 + 6 .

Solution

There are no brackets in our expression, multiplication and division are also absent, so we perform all the actions in the specified order. First, subtract three from seven, then add six to the remainder, and as a result we get ten. Here is a record of the entire solution:

7 − 3 + 6 = 4 + 6 = 10

Answer: 7 − 3 + 6 = 10 .

Example 2

Condition: in what order should the calculations be performed in the expression 6:2 8:3?

Solution

To answer this question, we reread the rule for expressions without parentheses, which we formulated earlier. We only have multiplication and division here, which means we keep the written order of calculations and count sequentially from left to right.

Answer: first, we divide six by two, multiply the result by eight, and divide the resulting number by three.

Example 3

Condition: calculate how much will be 17 − 5 6: 3 − 2 + 4: 2.

Solution

First, let's determine the correct order of operations, since we have here all the basic types of arithmetic operations - addition, subtraction, multiplication, division. The first thing we need to do is divide and multiply. These actions do not have priority over each other, so we perform them in the written order from right to left. That is, 5 must be multiplied by 6 and get 30, then 30 divided by 3 and get 10. After that we divide 4 by 2 , that's 2 . Substitute the found values into the original expression:

17 - 5 6: 3 - 2 + 4: 2 = 17 - 10 - 2 + 2

There is no division or multiplication here, so we do the remaining calculations in order and get the answer:

17 − 10 − 2 + 2 = 7 − 2 + 2 = 5 + 2 = 7

Answer:17 - 5 6: 3 - 2 + 4: 2 = 7.

Until the order of performing actions is firmly learned, you can put numbers over the signs of arithmetic operations, indicating the order of calculation. For example, for the problem above, we could write it like this:

If we have literal expressions, then we do the same with them: first we multiply and divide, then we add and subtract.

What are steps one and two

Sometimes in reference books all arithmetic operations are divided into operations of the first and second stages. Let us formulate the required definition.

The operations of the first stage include subtraction and addition, the second - multiplication and division.

Knowing these names, we can write the rule given earlier regarding the order of actions as follows:

Definition 2

In an expression that does not contain parentheses, first perform the actions of the second step in the direction from left to right, then the actions of the first step (in the same direction).

Order of evaluation in expressions with brackets

Parentheses themselves are a sign that tells us the desired order in which to perform actions. In this case, the desired rule can be written as follows:

Definition 3

If there are brackets in the expression, then the action in them is performed first, after which we multiply and divide, and then add and subtract in the direction from left to right.

As for the parenthesized expression itself, it can be considered as a component of the main expression. When calculating the value of the expression in brackets, we keep the same procedure known to us. Let's illustrate our idea with an example.

Example 4

Condition: calculate how much 5 + (7 − 2 3) (6 − 4) : 2.

Solution

This expression has parentheses, so let's start with them. First of all, let's calculate how much 7 − 2 · 3 will be. Here we need to multiply 2 by 3 and subtract the result from 7:

7 − 2 3 = 7 − 6 = 1

We consider the result in the second brackets. There we have only one action: 6 − 4 = 2 .

Now we need to substitute the resulting values into the original expression:

5 + (7 − 2 3) (6 − 4) : 2 = 5 + 1 2: 2

Let's start with multiplication and division, then subtract and get:

5 + 1 2:2 = 5 + 2:2 = 5 + 1 = 6

This completes the calculations.

Answer: 5 + (7 − 2 3) (6 − 4) : 2 = 6.

Do not be alarmed if the condition contains an expression in which some brackets enclose others. We only need to apply the rule above consistently to all parenthesized expressions. Let's take this task.

Example 5

Condition: calculate how much 4 + (3 + 1 + 4 (2 + 3)).

Solution

We have brackets within brackets. We start with 3 + 1 + 4 (2 + 3) , namely 2 + 3 . It will be 5 . The value will need to be substituted into the expression and calculate that 3 + 1 + 4 5 . We remember that we must first multiply, and then add: 3 + 1 + 4 5 = 3 + 1 + 20 = 24. Substituting the found values into the original expression, we calculate the answer: 4 + 24 = 28 .

Answer: 4 + (3 + 1 + 4 (2 + 3)) = 28.

In other words, when evaluating the value of an expression involving parentheses within parentheses, we start with the inner parentheses and work our way to the outer ones.

Let's say we need to find how much will be (4 + (4 + (4 - 6: 2)) - 1) - 1. We start with the expression in the inner brackets. Since 4 − 6: 2 = 4 − 3 = 1 , the original expression can be written as (4 + (4 + 1) − 1) − 1 . Again we turn to the inner brackets: 4 + 1 = 5 . We have come to the expression (4 + 5 − 1) − 1 . We believe 4 + 5 − 1 = 8 and as a result we get the difference 8 - 1, the result of which will be 7.

The order of calculation in expressions with powers, roots, logarithms and other functions

If we have an expression in the condition with a degree, root, logarithm or trigonometric function (sine, cosine, tangent and cotangent) or other functions, then first of all we calculate the value of the function. After that, we act according to the rules specified in the previous paragraphs. In other words, functions are equal in importance to the expression enclosed in brackets.

Let's look at an example of such a calculation.

Example 6

Condition: find how much will be (3 + 1) 2 + 6 2: 3 - 7 .

Solution

We have an expression with a degree, the value of which must be found first. We consider: 6 2 \u003d 36. Now we substitute the result into the expression, after which it will take the form (3 + 1) 2 + 36: 3 − 7 .

(3 + 1) 2 + 36: 3 - 7 = 4 2 + 36: 3 - 7 = 8 + 12 - 7 = 13

Answer: (3 + 1) 2 + 6 2: 3 − 7 = 13.

In a separate article devoted to calculating the values of expressions, we provide other, more complex examples of calculations in the case of expressions with roots, degrees, etc. We recommend that you familiarize yourself with it.

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In this lesson, the procedure for performing arithmetic operations in expressions without brackets and with brackets is considered in detail. Students are given the opportunity, in the course of completing assignments, to determine whether the meaning of expressions depends on the order in which arithmetic operations are performed, to find out whether the order of arithmetic operations differs in expressions without brackets and with brackets, to practice applying the learned rule, to find and correct errors made in determining the order of actions.

In life, we constantly perform some kind of action: we walk, study, read, write, count, smile, quarrel and make up. We perform these steps in a different order. Sometimes they can be swapped, sometimes they can't. For example, going to school in the morning, you can first do exercises, then make the bed, or vice versa. But you can’t go to school first and then put on clothes.

And in mathematics, is it necessary to perform arithmetic operations in a certain order?

Let's check

Let's compare the expressions:
8-3+4 and 8-3+4

We see that both expressions are exactly the same.

Let's execute actions in one expression from left to right, and in another from right to left. Numbers can indicate the order in which actions are performed (Fig. 1).

Rice. 1. Procedure

In the first expression, we will first perform the subtraction operation, and then add the number 4 to the result.

In the second expression, we first find the value of the sum, and then subtract the result 7 from 8.

We see that the values of the expressions are different.

Let's conclude: The order in which arithmetic operations are performed cannot be changed..

Let's learn the rule for performing arithmetic operations in expressions without brackets.

If the expression without brackets includes only addition and subtraction, or only multiplication and division, then the actions are performed in the order in which they are written.

Let's practice.

Consider the expression

This expression has only addition and subtraction operations. These actions are called first step actions.

We perform actions from left to right in order (Fig. 2).

Rice. 2. Procedure

Consider the second expression

In this expression, there are only operations of multiplication and division - These are the second step actions.

We perform actions from left to right in order (Fig. 3).

Rice. 3. Procedure

In what order are arithmetic operations performed if the expression contains not only addition and subtraction, but also multiplication and division?

If the expression without brackets includes not only addition and subtraction, but also multiplication and division, or both of these operations, then first perform multiplication and division in order (from left to right), and then addition and subtraction.

Consider an expression.

We reason like this. This expression contains the operations of addition and subtraction, multiplication and division. We act according to the rule. First, we perform in order (from left to right) multiplication and division, and then addition and subtraction. Let's lay out the procedure.

Let's calculate the value of the expression.

18:2-2*3+12:3=9-6+4=3+4=7

In what order are arithmetic operations performed if the expression contains parentheses?

If the expression contains parentheses, then the value of the expressions in the parentheses is calculated first.

Consider an expression.

30 + 6 * (13 - 9)

We see that in this expression there is an action in brackets, which means that we will perform this action first, then, in order, multiplication and addition. Let's lay out the procedure.

30 + 6 * (13 - 9)

Let's calculate the value of the expression.

30+6*(13-9)=30+6*4=30+24=54

How should one reason in order to correctly establish the order of arithmetic operations in a numerical expression?

Before proceeding with the calculations, it is necessary to consider the expression (find out if it contains brackets, what actions it has) and only after that perform the actions in the following order:

1. actions written in brackets;

2. multiplication and division;

3. addition and subtraction.

The diagram will help you remember this simple rule (Fig. 4).

Rice. 4. Procedure

Let's practice.

Consider the expressions, establish the order of operations and perform the calculations.

43 - (20 - 7) +15

32 + 9 * (19 - 16)

Let's follow the rules. The expression 43 - (20 - 7) +15 has operations in parentheses, as well as operations of addition and subtraction. Let's set the course of action. The first step is to perform the action in brackets, and then in order from left to right, subtraction and addition.

43 - (20 - 7) +15 =43 - 13 +15 = 30 + 15 = 45

The expression 32 + 9 * (19 - 16) has operations in parentheses, as well as operations of multiplication and addition. According to the rule, we first perform the action in brackets, then multiplication (the number 9 is multiplied by the result obtained by subtraction) and addition.

32 + 9 * (19 - 16) =32 + 9 * 3 = 32 + 27 = 59

In the expression 2*9-18:3 there are no brackets, but there are operations of multiplication, division and subtraction. We act according to the rule. First, we perform multiplication and division from left to right, and then from the result obtained by multiplication, we subtract the result obtained by division. That is, the first action is multiplication, the second is division, and the third is subtraction.

2*9-18:3=18-6=12

Let's find out if the order of actions in the following expressions is defined correctly.

37 + 9 - 6: 2 * 3 =

18: (11 - 5) + 47=

7 * 3 - (16 + 4)=

We reason like this.

37 + 9 - 6: 2 * 3 =

There are no brackets in this expression, which means that we first perform multiplication or division from left to right, then addition or subtraction. In this expression, the first action is division, the second is multiplication. The third action should be addition, the fourth - subtraction. Conclusion: the order of actions is defined correctly.

Find the value of this expression.

37+9-6:2*3 =37+9-3*3=37+9-9=46-9=37

We continue to argue.

The second expression has brackets, which means that we first perform the action in brackets, then from left to right multiplication or division, addition or subtraction. We check: the first action is in brackets, the second is division, the third is addition. Conclusion: the order of actions is defined incorrectly. Correct the errors, find the value of the expression.

18:(11-5)+47=18:6+47=3+47=50

This expression also contains brackets, which means that we first perform the action in brackets, then from left to right multiplication or division, addition or subtraction. We check: the first action is in brackets, the second is multiplication, the third is subtraction. Conclusion: the order of actions is defined incorrectly. Correct the errors, find the value of the expression.

7*3-(16+4)=7*3-20=21-20=1

Let's complete the task.

Let's arrange the order of actions in the expression using the studied rule (Fig. 5).

Rice. 5. Procedure

We do not see numerical values, so we will not be able to find the meaning of expressions, but we will practice applying the learned rule.

We act according to the algorithm.

The first expression has parentheses, so the first action is in parentheses. Then from left to right multiplication and division, then from left to right subtraction and addition.

The second expression also contains brackets, which means that we perform the first action in brackets. After that, from left to right, multiplication and division, after that - subtraction.

Let's check ourselves (Fig. 6).

Rice. 6. Procedure

Today in the lesson we got acquainted with the rule of the order of execution of actions in expressions without brackets and with brackets.

Bibliography

M.I. Moro, M.A. Bantova and others. Mathematics: Textbook. Grade 3: in 2 parts, part 1. - M .: "Enlightenment", 2012.
M.I. Moro, M.A. Bantova and others. Mathematics: Textbook. Grade 3: in 2 parts, part 2. - M .: "Enlightenment", 2012.
M.I. Moreau. Mathematics lessons: Guidelines for teachers. Grade 3 - M.: Education, 2012.
Regulatory document. Monitoring and evaluation of learning outcomes. - M.: "Enlightenment", 2011.
"School of Russia": Programs for elementary school. - M.: "Enlightenment", 2011.
S.I. Volkov. Mathematics: Testing work. Grade 3 - M.: Education, 2012.
V.N. Rudnitskaya. Tests. - M.: "Exam", 2012.

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Homework

1. Determine the order of actions in these expressions. Find the meaning of expressions.

2. Determine in which expression this order of actions is performed:

1. multiplication; 2. division;. 3. addition; 4. subtraction; 5. addition. Find the value of this expression.

3. Compose three expressions in which the following order of actions is performed:

1. multiplication; 2. addition; 3. subtraction

1. addition; 2. subtraction; 3. addition

1. multiplication; 2. division; 3. addition

Find the meaning of these expressions.

Task 192.

Complete the tasks orally.

1) Find the sum of the numbers 5 and 2. Subtract this sum from the number 10.
2) To the number 8 add the difference between the numbers 9 and 3.

Solution:

1) 10 - (5 + 2) = 3
2) 8 + (9 - 3) = 14

Task 193.

The roll contained 15 m of fabric. The first buyer bought 5 m of fabric, and the second 3 m. How many meters of fabric are left on the roll?
To find out how many meters of fabric were left on the roll, the seller did this: he calculated how many meters of fabric he sold in total, and then subtracted the resulting number from 15.

15 - (5 + 3) = 7 (m)

The brackets mean that first, it is clear to find the sum, and then perform the subtraction operation.

Task 194.

Read and calculate.
From the number 12 subtract the sum of the numbers 7 and 2.

To the number 8 add the difference between the numbers 13 and 6.

Solution:

1) 12 - (7 + 2) = 3
2) 8 + (13 - 6) = 15

Task 195.

There were 12 cars in the parking lot. First 4 cars left, and then 3 more. How many cars are left in the parking lot?

Solution:

1) 12 - (4 + 3) = 5
Answer: 5 cars.

Task 196.

One squirrel has 9 nuts and the same number - the other. How many nuts do squirrels have?

Solution:

1) 9 + 9 = 18
Answer: 18 nuts.

Task 197.

Read and calculate.

1) From the number 14 subtract the difference between the numbers 7 and 2.
2) To the number 8 add the sum of the numbers 3 and 6.

Solution:

1) 14 - (7 - 2) = 9
2) 8 + (3 + 6) = 17

Task 198.

There were 13 trucks in the parking lot, and 8 fewer cars. Another 6 cars arrived. How many cars were in the parking lot?

Solution:

1) (13 - 8) + 6 = 11
Answer: 11 cars.

Task 199.

Complete and solve the problem.
There are 7 computers in one class and 2 computers in the other... .

Solution:

One class has 7 computers and the other has 2 computers less. How many computers are in 2 classrooms together.

1) 7 - 2 = 5
2) 7 + 5 = 12
Expression: (7 - 2) + 7 = 12
Answer: 12 computers.

Task 200.

Solve examples.

Solution:

Task 202.

From each addition example, make two subtraction examples.

9 + 7 = 16

14 - 6 = 8

Solution:

Task 204.

Solution:

1) Add 9 and 7, equals 16. 9 plus 7 equals 16. 9 times 7 equals 16. The sum of nine and seven equals sixteen.
2) 14 minus 6 equals 8. 14 minus 6 equals 8. 14 minus 6 equals 8. The difference between fourteen and six equals eight.

Task 205.

In the morning, 9 liters of milk were milked from a cow, | and in the evening - 1 liter less. | 3 liters of milk from evening milking left, | and the rest was sold. How many liters of milk from evening milking were sold?
Read the entire issue. Think about what it says.
Read the problem in parts, into which it is divided by lines.
Solve the problem.
Solution Plan

1) How many liters of milk did you milk in the evening?
2) How many liters of milk from evening milking were sold?

Solution:

1) 9 - 1 = 8
2) 8 - 3 = 5
Expression: (9 - 1) - 3 = 5
Answer: 5 liters.

Task 206.

On Saturday father and son cut 4 trees together. On Sunday, the father cut 3 trees and the son cut the same number of trees. How many trees did they cut in 2 days?

Solution:

1) 3 + 3 = 6
2) 4 + 6 = 10
Expression: 4 + 3 + 3 = 10
Answer: 10 trees.

Task 207.

Solve examples.

Solution:

14 - 6 - 6 = 2	7 + 5 + 1 = 13	16 - 8 + 1 = 9
14 - (6 - 6) = 14	7 + (5 + 1) = 13	16 - (8 + 1) = 7

Task 208.

Draw a picture and solve it.

Solution:

There were 12 apples under the tree. One hedgehog took 4 apples, and the other 3 more. How many apples are left under the tree?

1) 4 + 3 = 7
2) 12 - 7 = 5
Expression: 12 - (4 + 3) = 5
Answer: 5 apples.