Subtraction Within 10: practice solutions, Grade 1 – download the PDF

1 Cross out and count ★★★

a) 2 stickers are crossed out, so 2 were used.

b) We count the stickers that are not crossed out: there are 4 left.

c) \( 6 - 2 = 4 \). There are 4 stickers left.

2 Complete the facts ★★★

a) \( 5 - 1 = 4 \)
b) \( 8 - 0 = 8 \) because taking away nothing changes nothing.
c) \( 9 - 9 = 0 \) because taking away everything leaves nothing.
d) \( 7 - 2 = 5 \)
e) \( 10 - 4 = 6 \)

3 Birds on a fence ★★★

Draw 8 circles. Cross out 3 of them. Count the circles that are not crossed out: there are 5.

\( 8 - 3 = 5 \). There are 5 birds still on the fence.

4 Match the picture ★★★

The picture starts with 9 counters and 4 are crossed out, so we take away. The sentence is \( 9 - 4 = 5 \).

\( 5 + 4 = 9 \) adds counters, and \( 4 - 9 \) starts with the smaller number. So only \( 9 - 4 = 5 \) matches. There are 5 counters left.

5 Hop back on the number line ★★★

a) From 7 we hop back to 6, then 5, then 4. We land on 4.

b) \( 7 - 3 = 4 \).

6 Marbles in a bag ★★★

The whole is 8 and one part is 3. We subtract: \( 8 - 3 = 5 \).

Check with addition: \( 3 + 5 = 8 \). There are 5 blue marbles.

7 True or false? ★★★

a) True: \( 6 - 2 = 4 \).
b) False: taking away all 5 leaves 0, so \( 5 - 5 = 0 \).
c) True: \( 9 - 1 = 8 \).
d) False: \( 4 - 3 = 1 \).

8 Cookies on a plate ★★★

We start with 10 and take away 4: \( 10 - 4 = 6 \).

There are 6 cookies left.

9 Plus or minus? ★★★

a) 7 gets smaller to 5, so it is minus: \( 7 - 2 = 5 \).
b) 7 is bigger than 4, so it is plus: \( 4 + 3 = 7 \).
c) 3 is smaller than 9, so it is minus: \( 9 - 6 = 3 \).
d) 10 is bigger than 2, so it is plus: \( 2 + 8 = 10 \).

10 A fact family ★★★

The whole is 9 and the parts are 4 and 5.

Addition: \( 4 + 5 = 9 \) and \( 5 + 4 = 9 \).
Subtraction: \( 9 - 4 = 5 \) and \( 9 - 5 = 4 \).

11 Let addition help ★★★

a) \( 7 + 3 = 10 \), so \( 10 - 7 = 3 \).
b) \( 5 + 3 = 8 \), so \( 8 - 5 = 3 \).
c) \( 4 + 2 = 6 \), so \( 6 - 4 = 2 \).

12 On the playground ★★★

We start with 9 and take away 6: \( 9 - 6 = 3 \).

Check: \( 6 + 3 = 9 \). There are 3 children still outside.

13 Find the hidden number ★★★

a) \( 2 + 6 = 8 \), so the box is 6: \( 8 - 6 = 2 \).
b) Put the 4 back: \( 3 + 4 = 7 \). The box is 7: \( 7 - 4 = 3 \).
c) Nothing was taken away, so the box is 0: \( 10 - 0 = 10 \).

14 Who has more left? ★★★

Leo: \( 9 - 5 = 4 \) crayons.
Ana: \( 7 - 2 = 5 \) crayons.

Since 5 is greater than 4, Ana has more crayons left.

15 How many at the start? ★★★

The sentence is \( \square - 4 = 5 \).

Put the 4 cars back: \( 5 + 4 = 9 \). So \( 9 - 4 = 5 \) is true. Sam had 9 cars at the start.

16 Find the mistake ★★★

a) When we take away, the group gets smaller. 8 is bigger than 6, so the answer cannot be 8. Ben added instead of subtracting.

b) The correct answer is \( 6 - 2 = 4 \). Check: \( 4 + 2 = 6 \).

17 The odd one out ★★★

The first three facts use only the numbers 2, 7 and 9. The last fact uses 9, 3 and 6, so \( 9 - 3 = 6 \) is the odd one out. (It is a true fact, but it belongs to the family of 3, 6 and 9.)

18 Equal answers ★★★

a) \( 10 - 6 = 4 \). We need \( \square - 2 = 4 \), and \( 4 + 2 = 6 \). The box is 6: \( 6 - 2 = 4 \).

b) \( 9 - 4 = 5 \). We need \( 8 - \square = 5 \), and \( 5 + 3 = 8 \). The box is 3: \( 8 - 3 = 5 \).

19 Two steps ★★★

Step 1: \( 10 - 3 = 7 \). There are 7 apples after Dad takes some.

Step 2: \( 7 - 2 = 5 \). There are 5 apples after Mia takes some.

There are 5 apples left in the bowl.

20 Mystery number ★★★

The sentence is \( \square - 6 = 3 \).

Put the 6 back: \( 3 + 6 = 9 \). I am 9. Check: \( 9 - 6 = 3 \), which is true.