Without the line
No number line near you? Four short questions give the answer.
Step 1 of 3
- (−6) − (−9).
- Rewrite: add 9.
- Different signs. 9 − 6 = 3.
A number below 0 points left. A number above 0 points right.
Rule — four short questions, in order:
- Is it a take-away? Rewrite it as an add.
- Do both numbers point the same way? Add the sizes. Keep that side.
- Different ways? Take the smaller size from the bigger. Keep the bigger move's side.
- Same size, opposite ways? The answer is 0.
Try (−6) − (−9) = (−6) + 9. The sizes are 6 and 9 steps. So 9 − 6 = 3. The bigger move points right. So the answer is 3.
Watch out!
4 − 11 is not 7. Check on the line: 11 steps left of 4 stop at −7. The line is a good check for an answer that looks wrong.
Tap the answer in the lab. Then check it on the line.
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