Think of a number line. Adding a positive number moves right; subtracting a positive number moves left. So −7 + 3 = −4 and 2 − 9 = −7.
Adding a negative is the same as subtracting its opposite: 5 + (−8) = 5 − 8 = −3. Subtracting a negative is the same as adding: −4 − (−6) = −4 + 6 = 2. A useful picture is a hot-air balloon: adding weights (negatives) makes it sink, and removing weights makes it rise.
Worked example
−12 − (−5) =
- Subtracting a negative is the same as adding: −12 + 5.
- Start at −12 and move 5 to the right.
Answer:−7
Key words
- integer
- a whole number, positive, negative or zero
- opposite
- the number the same distance from 0 on the other side
- additive inverse
- a number that adds to 0, like 5 and −5
Practise this
New questions every time.
Common Core-referenced: 7.NS.A.1