Two-digit ± one-digit, no regrouping
When a one-digit number is added or subtracted without crossing a ten, only the ones digit changes: 43 + 5 = 48 and 67 − 4 = 63. It is the first step in mental math within 100, before regrouping comes in.
How to solve this
- Adding or subtracting a single digit without regrouping only changes the ones digit; the tens stay the same.
- Keep the tens part fixed and calculate only the ones part: 53 + 4 = 5 tens + (3 + 4) ones = 57.
- Check that the tens digit is unchanged and the ones digit is within 0–9.
Examples
46 + 7 = ?
53
82 - 25 = ?
57
34 + 21 = ?
55
Practice problems with answers
Solve these problems on paper or out loud, then check the answer key. The online practice and the printable worksheet give a new set every time.
- ___ + 1 = 89
- ___ + 5 = 95
- 61 − 1 = ___
- 17 − 5 = ___
- 50 + 4 = ___
- ___ + 3 = 19
- ___ − 1 = 41
- 45 + ___ = 48
Show answers
- 88
- 90
- 60
- 12
- 54
- 16
- 42
- 3