Fact Families (Addition & Subtraction to 20) — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 4 + 9 = 13
Take 1 from the 4 and give it to 9 to make 10, then add the 3 left to get 13. Making a ten first makes adding near-ten numbers easier.
2. 9 + 4 = 13
Addition can be done in either order, so 9 + 4 equals the same 13 as 4 + 9. These are turn-around facts in the 4, 9, 13 family.
3. 13 - 4 = 9
Since 4 + 9 = 13, taking 4 away from 13 must leave the other part, 9. Subtraction always reverses a related addition fact.
4. 13 - 9 = 4
Count up from 9 to 13 (10, 11, 12, 13) and you jump 4 times. So 13 - 9 = 4, finishing the 4, 9, 13 fact family.
5. 8 + 5 = 13
Move 2 from the 5 to the 8 to make 10, then add the 3 left for 13. This make-ten strategy is a Grade 1 favorite.
6. 5 + 8 = 13
Switching the parts does not change the whole, so 5 + 8 also equals 13. The numbers 5, 8, and 13 build a new fact family.
7. 13 - 8 = 5
Ask yourself, 8 plus what equals 13? Count 9, 10, 11, 12, 13 to find you jumped 5, so 13 - 8 = 5.
8. 13 - 5 = 8
Remove the 5 part from the whole 13, leaving 8 behind. These related facts show how subtraction works as the opposite of addition.
9. 7 + 9 = 16
Think of 7 + 9 as 7 + 10 - 1, which gives 17 - 1 = 16. Using tens nearby is a quick way to add bigger numbers.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
5 + 6
→ 11
7
18 - 9
→ 9
9
4 + 8
→ 12
11
16 - 9
→ 7
12
Work each fact before drawing lines: 5 + 6 is the double 5 + 5 plus one more for 11, 18 - 9 is the doubles fact 9 + 9 reversed to 9, 4 + 8 makes 12 by adding two to ten, and 16 - 9 leaves 7. Each answer comes from a different fact family.