Definition
Compensation
Changing numbers to friendlier ones, then balancing the change to keep the answer exact.
What it means
Sometimes a number is close to an easier number such as 10, 50, or 100. You can move to that friendly number, but you must balance what you changed. The balancing step is what keeps compensation exact instead of turning it into an estimate.
Remember it
Make it friendly, then pay back the change.
Example
For 48 + 27, move 2 from 27 to 48: 50 + 25 = 75. One addend rose by 2 and the other fell by 2, so the total stayed the same.
Watch for
Changing 48 + 27 to 50 + 30 gives an estimate, not compensation, because the extra 5 was not balanced.
Common mix-up
Compensation keeps an exact value. Rounding usually replaces it with an approximate value.
Exact meaning
Compensation is a calculation strategy that makes a convenient change to one or more numbers and applies a balancing adjustment so the original expression keeps the same value.