Adding within 100

Mathematics · Addition & Subtraction · ages 6-7

Name ______________________ Date ____________

38 + 40 = ?
- 42
- 68
- 78
What is 55 + 20?
Answer: ______________
What is 38 + 40?
- 78
- 68
- 88
- 70
You want to add 46 + 7 by first jumping to the next ten. How many do you add to 46 to reach 50?
- 3
- 4
- 7
What is 37 + 20?
Answer: ______________
What is 64 + 8?
- 74
- 72
- 62
- 70
What is 29 + 30?
Answer: ______________
Maya lines up 46 and 7 to add them, with the 7 written under the 6. Why does the 7 go under the 6, and not under the 4?
- Ones line up under ones, and tens line up under tens
- 7 is bigger than 4, so it goes on the right
- It does not matter where she writes it
Tom adds 27 + 8 by bridging to the next ten. He says: '27 + 3 = 30, then 30 + 8 = 38.' What did Tom get wrong?
- He should have added 30 + 5, since he already used 3 of the 8
- He should have started from a different ten
- 27 + 3 does not equal 30
What is 48 + 25?
- 71
- 83
- 73
- 63

Answer key

For grown-ups. Fold this page away before handing over the rest.

78 · 3 tens plus 4 tens make 7 tens, and the 8 ones stay the same: 38 + 40 = 78.
75 · 55 plus 20 equals 75.
78 · 38 plus 40 equals 78.
4 · 46 needs 4 more to reach the next ten, which is 50.
57 · 37 plus 20 equals 57.
72 · 64 plus 8 equals 72. Hop 6 to 70, then 2 more.
59 · 29 plus 30 equals 59.
Ones line up under ones, and tens line up under tens · Each column holds one place value. The 6 and 7 are both ones, so they share a column.
He should have added 30 + 5, since he already used 3 of the 8 · Tom used 3 of the 8 to reach 30, so only 5 ones are left to add. 30 + 5 = 35, not 38.
73 · 48 plus 25 equals 73.