Number houses with tens
In a number house the roof number is the total, and each floor holds two numbers that add up to it. With tens, 70 can be 10 + 60, 20 + 50 or 30 + 40, and children find the missing part of each pair.
How to solve this
- A calculation house splits one number (the "roof") into two parts (the "floors") that add up to it.
- If you know the roof and one floor, subtract to find the missing floor.
- Check that both floors add up exactly to the roof number.
Examples
Number house 70: 30 + __
40
Number house 56: 20 + __
36
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.
- Target 70: 30 + ___ = 70
- Target 50: ___ + 40 = 50
- Target 80: ___ + 70 = 80
- Target 40: ___ + 20 = 40
- Target 90: ___ + 50 = 90
- Target 90: ___ + 80 = 90
- Target 50: 10 + ___ = 50
- Target 100: ___ + 30 = 100
Show answers
- 40
- 10
- 10
- 20
- 40
- 10
- 40
- 70