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.
Teach it
Where it is taught, with guided notes, practice, homework, an exit ticket and an interactive Teacher Deck.
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.