Partitioning to twenty
You learn that every number from 11 to 19 is made of one ten and some ones.
How to work it out
- Partition the teen number into ten and ones: 14 is 10 and 4.
- Identify the given part; the other part is the answer.
10 + _ = 14
- Partition 14 into 10 and 4.
- The 10 is already there.
- The missing part is 4, so 10 + 4 = 14.
More examples
6 + _ = 16
- Partition 16 into 10 and 6.
- The 6 is already there.
- The missing part is 10, so 6 + 10 = 16.
10 + _ = 19
- Partition 19 into 10 and 9.
- The 10 is already there.
- The missing part is 9, so 10 + 9 = 19.