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Cogito

Grade 2 Math · Chapter 4 · Lesson 8

Practice Worksheet

Checking by Adding

Add your answer back and see if you return.

10 problems · about 12 minutes · 2.NBT.B.9, 2.OA.A.1

NameDate

Figure — use these to answer the problems

Two parts make a whole. Every subtraction has an addition that checks it.
  • 35 + 27 = 62
The answer35
What was taken27
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

2 problems

  1. From “Subtracting With a Broken Ten”

    45 − 28 = ?

    Answer

  2. From “Breaking a Ten Apart”

    6 tens and 12 ones is which number?

    Answer

Warm Up

Straightforward practice. Get the method working first.

4 problems

  1. 75 − 38 = ?

    Answer

  2. How do you check a subtraction?

    • Add the answer to what was taken away.
    • Subtract it a second time.

  3. 61 − 34 = ?

    Answer

  4. Check it: what is 27 + 34?

    Answer

Build It Up

The same ideas with more to keep track of.

2 problems

  1. 90 − 47 = ?

    Answer

  2. Check it: what is 43 + 47?

    Answer

Stretch Yourself

Mixed problems. Work out what kind of question it is before you start.

2 problems

  1. Checking Up

    Ana says 84 − 29 = 55. Check it: what is 55 + 29?

    Answer

  2. A Wrong Answer

    Leo says 52 − 38 = 24. What is 24 + 38?

    Answer