Definition
Make-ten strategy
The make-ten strategy splits a number so one part completes ten, making the rest easier to calculate.
What it means
Ten is easy to work with. Find how much the first number needs to reach ten, split the other number into that amount and what remains, then finish. You have changed the route, not the sum or difference.
Remember it
Fill the ten first; carry the leftover next.
Example
For 9 + 6, split 6 into 1 + 5. Then 9 + 1 + 5 = 10 + 5 = 15.
Watch for
You may only split and regroup numbers in a way that keeps their total unchanged.
Common mix-up
Making ten does not mean rounding 9 + 6 to 10; the leftover 5 still has to be added.
Exact meaning
The make-ten strategy decomposes an addend or subtrahend so an intermediate calculation reaches 10, or another power of ten, without changing the value of the expression.