Subtract within 20

10 - 7 = ______

• 1

• 2

• 3

• 4

• 17

Answer explanation

7 + ______ = 10 is the same as 10 - 7 = ________

18 - 6 = ________

• 12

• 13

• 14

• 15

Answer explanation

Notice that both 18 and 6 are even numbers. That means that the answer will also be an even number ( 2, 4, 6, 8, 10,12, 14, etc.).

11 - 6 =_______

• 4

• 5

• 6

• 7

Answer explanation

If you remember that 6 x 2 = 12 (or 6 + 6) it can help you solve this problem. Since it is 11 - 6, and you know that 12 - 6 is 6, you can just subtract 1 from your answer to 12-6 to get the answer to 11 - 6 (5).

19 - 3 = ________

• 13

• 14

• 15

• 16

• 17

Answer explanation

You can see that 9 is greater than 3, so you can just subtract 9 from 3, then bring the one (in the ten's place) down to answer the problem.

19

-3

________

16

20 - 8 = _______

• 11

• 12

• 13

• 14

Answer explanation

Another way to quick do the math in your head is to just subtract 8 from 10 (10 - 8 = 2) and then add 10 to the answer to find the answer for 20 - 8 (which is 12).

13 - 6 = _______

• 9

• 8

• 7

• 6

• 5

17 - 14 = ________

• 2

• 3

• 4

• 5

16 - 8 = ________

• 8

• 9

• 6

• 7

20 - 9 = _____

• 2

• 12

• 1

• 11

19 - 9 =_______

• 9

• 10

• 11

• 12