number · Year 2 · AC9M2N02
Partition numbers in different ways
A number can be split into parts in many ways. 46 is 40 + 6, but if you break one ten into ones it is also 30 + 16. Nothing is lost: the parts still add to 46. In the same way 352 = 200 + 150 + 2, and because every hundred is 10 tens, 352 is 35 tens and 2 ones. Check by adding the parts back together.
Sample questions
49 = 30 + ?
- 49 is 4 tens and 9 ones.
- 30 uses only 3 tens, so 1 ten is left over with the 9 ones.
- 1 ten and 9 ones make 19, so 49 = 30 + 19.
Answer: 19
43 = 30 + ?
- 43 is 4 tens and 3 ones.
- 30 uses only 3 tens, so 1 ten is left over with the 3 ones.
- 1 ten and 3 ones make 13, so 43 = 30 + 13.
Answer: 13
31 = 20 + ?
- 31 is 3 tens and 1 ones.
- 20 uses only 2 tens, so 1 ten is left over with the 1 ones.
- 1 ten and 1 ones make 11, so 31 = 20 + 11.
Answer: 11