Subtraction bridging ten
You learn subtractions that cross ten by going back to exactly ten first.
How to work it out
- Split the second number to land on ten.
- Subtract to ten first.
- Then subtract the rest.
15 − 7
- Split 7 into 5 and 2, because 15 − 5 = 10.
- Take away the 5 first: 10.
- Then take away the 2: 10 − 2 = 8.
More examples
13 − 8
- Split 8 into 3 and 5, because 13 − 3 = 10.
- Take away the 3 first: 10.
- Then take away the 5: 10 − 5 = 5.
12 − 4
- Split 4 into 2 and 2, because 12 − 2 = 10.
- Take away 2 first: 10.
- Then take away the other 2: 10 − 2 = 8.