Math Core

Lesson 5.3 · Subtraction

Subtracting within 10

Now let's take away from bigger groups, up to 10. You can use a picture, your fingers or counting back.

Use rows of 5

Put things in rows of 5. Cross out the ones you take away. Then count what is left.

Worked example: Crayons

Find 8−38 - 3.

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Start with 8 crayons. Take away 3. The whole top row is left. That is 5.

8−3=58 - 3 = 5

Count back

You can also count back. Start at the first number. Say one number back for each one you take away. Hold up a finger each time so you know when to stop.

Counting back

To find 9−29 - 2, start at 9. Count back 2: 8, 7. The last number you say is the answer.

9−2=79 - 2 = 7

Worked example: Count back 3

Find 7−37 - 3.

Start at 7. Count back 3: 6, 5, 4.

7−3=47 - 3 = 4

Worked example: Ten fingers

Find 10−410 - 4.

Hold up 10 fingers. Put down 4. Count the fingers still up: one, two, three, four, five, six.

10−4=610 - 4 = 6

Common mistake

When you count back, don't say the starting number. For 7−37 - 3, start at 7 and say 6, 5, 4. Do not say "7, 6, 5."

Practice

Practice 1

Find 6−26 - 2.

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Type a number.

Practice 2

Find 9−19 - 1.

Type a number.

Practice 3

Find 7−27 - 2.

Type a number.

Practice 4

Find 8−58 - 5.

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Type a number.

Practice 5

Find 10−310 - 3.

Type a number.

Practice 6

Find 9−99 - 9.

Type a number.

Practice 7

Find 10−610 - 6.

Type a number.

Practice 8

Which is the same as 6−16 - 1?