Two dashes on one line
A lift is on level 5. The parking area is on level −3. How many levels apart?
Step 1 of 3
- Start at 5.
- Take away −3.
- Two dashes turn the walk right. Land on 8.
From −3 to 0 is 3 levels. From 0 to 5 is 5 more. So they are 8 levels apart.
The gap is 5 − (−3). It has two dashes: the take-away sign and the minus of −3.
Rule: taking away a number below zero walks you right. The opposite of −3 is 3, so 5 − (−3) is 5 + 3. Adding 3 walks right.
| Written | Rewritten | Lands on |
|---|---|---|
| 5 − (−3) | 5 + 3 | 8 |
| (−2) − (−6) | (−2) + 6 | 4 |
| (−9) − (−4) | (−9) + 4 | −5 |
| 5 − 3 | 5 + (−3) | 2 |
Row three still ends below zero. Walking right does not always cross zero.
Slide the number taken away in the lab. Watch which way the walk goes.
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