Grade 3 · Math · Unit 3 of 14
Facts to 20
Quick adding and subtracting
What your child practises
Building fast, flexible recall of addition and subtraction facts to 20 with strategies like making ten, near doubles, fact families and thinking addition to subtract.
Nunavut Curriculum approved guide: Alberta Mathematics K–9 (2007), Number · mental math strategies for addition facts and related subtraction facts
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
8 + 8 = 16. So what is 8 + 9?
8 + 9 = ?
- 15
- 17
- 16
- 19
17
Hint: Use the double 8 + 8 = 16. 8 + 9 is 1 more, so it's 17.
Question 2
Ravi has 12 stickers and gives 7 to a friend. How many stickers are left?
⭐answer box
5
Hint: Take away: 12 − 7. Take away 2 to get to 10, then take away 5 more: 10 − 5 = 5. Or think 7 + ? = 12.
Question 3
Make a ten! What number goes in the box?
7 + 8 = 10 +
- 6
- 8
- 5
- 4
5
Hint: 7 needs 3 more to make 10. Take 3 from 8, and 5 is left over.
Question 4
What is 9 + 8?
9 + 8 = ?
answer box
17
Hint: Use a double: 8 + 8 = 16, and 1 more makes 17.
Question 5
Which fact is in the same family as 6 + 9 = 15?
6 + 9 = 15
- 15 + 6 = 21
- 9 − 6 = 3
- 9 + 6 = 15
- 15 − 7 = 8
9 + 6 = 15
Hint: A fact family uses the same three numbers: 6, 9 and 15. Find the fact that uses only those numbers.
Question 6
What is 12 − 7?
12 − 7 = ?
answer box
5
Hint: Take away 2 to get to 10, then take away 5 more: 10 − 5 = 5. Or think 7 + ? = 12.