Subtraction Within 20 (Regrouping) — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. What is 15 - 8?
A) 6
B) 7
C) 8
D) 9
Split 8 into 5 and 3: 15 - 5 = 10, then 10 - 3 = 7, so 15 - 8 = 7.
2. What is 13 - 6?
A) 5
B) 8
C) 6
D) 7
Break 6 into 3 and 3: 13 - 3 = 10, then 10 - 3 = 7.
3. What is 17 - 9?
A) 8
B) 7
C) 9
D) 6
Because 9 + 8 = 17, the missing partner is 8, so 17 - 9 = 8.
4. What is 14 - 7?
A) 6
B) 8
C) 9
D) 7
This is a doubles fact: 7 + 7 = 14, so taking 7 from 14 leaves 7.
Part B: Fill in the Blank
Write the correct answer on each line.
1. 16 - 9 = 7
Count up from 9 to 16: 10, 11, 12, 13, 14, 15, 16 — that is 7 jumps, so the answer is 7.
2. 11 - 5 = 6
Split 5 into 1 and 4: 11 - 1 = 10, then 10 - 4 = 6.
3. 18 - 9 = 9
Doubles fact: 9 + 9 = 18, so 18 - 9 must leave 9.
4. 12 - 8 = 4
Break 8 into 2 and 6: 12 - 2 = 10, then 10 - 6 = 4.
5. 15 - 6 = 9
Split 6 into 5 and 1: 15 - 5 = 10, then 10 - 1 = 9.