7th Grade · The Number System
KCC
7.NS.A.1d
Definition
A method for subtracting integers: Keep the first number, Change subtraction to addition, Change the sign of the second number. Works for all integer subtraction.
Examples
- (−3) − (−5) = (−3) + (+5) = +2.
- 7 − 9 = 7 + (−9) = −2, and −4 − (−6) = −4 + 6 = 2.
Key rule
KCC turns every subtraction into an addition.
Memory hook
Keep - Change - Change.