Page 150 - NUMINO TG_2A

09Math Balance Unit

3 Use addition, subtraction and a related fact to find the missing 3. The boxes represent certain numbers.
Have students find the missing numbers.
number.
Method 1: Use the related addition and
18- =7 -= subtraction of fact families to find the missing
=- numbers in the blanks.
=18-7=11
=7 Use a related fact, addition, and
subtraction to find the missing
number.

a 31- =16 b -14=35 18 11 7 18 11 7
=31-16 =35+14
= 15 = 49 11 18 7 18 11 7

Method 2: Use the 4-step method.

c 51- =30 d -16=47 Understand the Question
= 21 = 63
Q: What are we trying to find?

A: The missing number.

Plan the Process

4 Write the number sentence to find the missing number. Q: How can we solve it?

A: Use to represent the missing

a 32 subtracted by an unknown 32- =14 number.
number is 14. =18
Solve the Problem

b Q: Write a subtraction sentence.
43 is 8 less than an unknown
number. -8=43 A: 18 7.
=51
Look Back
9. Math Balance 83
Q: What is the answer?

A: 11.

Problem: Read the following problem and write sentences using , and find the missing number.
Adding 18 to 35 and subtract a certain number to get 27.

Solution: If the missing number is represented by , we can express the problem as follows:

35 18 27, 53 27, so 53 27 26.

Answer: 18 35 27, 26

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