Test Review

Damian was solving the subtraction problem:

650 - 62

He wanted to decompose 62 to make it easier to subtract.

Pick the equation that best shows how Damian can do this.

• 650 - 50 + 12

• 650 - 60 + 2

• 650 - 50 - 12

• 650 - 52 - 9

Answer explanation

When we decompose a number to help us subtract, we keep the same operation.

650 - 50 = 600

590 - 12 = 588

Which is the same as:

650 - 62 = 588

Pick TWO equations that add up to 66

• 11 + 39 + 16

• 21 + 14 + 11 + 20

• 14 + 26 + 45 + 29

• 19 + 27 + 49

What equation is represented on the number line?

• 390 + 136 = ?

• 526 - 136 = ?

• 390 + 126 = ?

• 526 - 126 = ?

265 + 347 =

• 612

• 602

• 622

• 512

Selene is trying to solve 138 – 64 with place value blocks.

The picture shows her work.

Which of the following is a true statement?

• Selene is wrong. She subtracted a hundred

  and there is no hundred in 64.

• Selene is wrong because she crossed out 164 and not 64

  .

• Selene is correct because she traded one 100 for ten 10s so she could subtract.

• Selene is wrong because she added more tens to her problem, she is supposed to be subtracting, not adding.

Answer explanation

Selene unbundled a hundred into 10 tens because she didn't have enough.

Whenever we do not have enough units, we unbundle from the next highest place value!

What expression is shown by the number line?

• 334 + 126

• 460 - 334

• 460 - 126

• 334 + 460

Answer explanation

When we subtract we start on the right!

Pick TWO equations that equal 35.

• 10 + 20 + 5

• 12 + 15 + 20

• 13 + 11 + 10 + 1

• 20 + 25 + 13

• 5 + 5 + 10 + 10

Tristan drew the number line below to help solve a math problem. He found out that his answer was 668.

Which is the best choice for the equation he was solving?

• 668 + 123 = ?

• 791 - 133 = ?

• 691 - 123 = ?

• 791 - 123 = ?

Answer explanation

When we subtract we start on the right with 791.

We count up the jumps to find out how much he subtracted. 100 + 10 + 10 + 3 = 123

791 - 123 = 668

29 + 55 + 21 + 73 =

• 168

• 78

• 178

• 188

Select the choice below that shows another way to write this equation.

250 - 126 = ?

• ? + 126 = 250

• 250 + ? = 126

• ? - 250 = 126

• 126 - 250 = ?

Answer explanation

Every equation has an opposite.

250 - 126 = 124

so the opposite equation is:

124 + 126 = 250