Adding and subtracting decimals, step by step
Adding and subtracting decimals is one skill with one rule: line up the decimal points.
The question
13.49 − 13.17
13.49 13.17 0.32
- 13.49 − 13.17. Line the POINTS up under each other — not the right-hand ends. Right-aligning is what turns 12.5 + 3.75 into a tidy-looking wrong answer.
- 9 take away 7 leaves 2.
- 4 take away 1 leaves 3.
- 3 take away 3 leaves 0.
- 1 take away 1 leaves nothing — and a nothing at the front is not written, so the answer starts one place along.
- The point in the answer comes straight down from the ones above it — it was never moved, only lined up. 13.49 − 13.17 = 0.32.
How it works.
- 01
13.49 − 13.17. Line the POINTS up under each other — not the right-hand ends. Right-aligning is what turns 12.5 + 3.75 into a tidy-looking wrong answer.
- 02
9 take away 7 leaves 2.
- 03
4 take away 1 leaves 3.
- 04
3 take away 3 leaves 0.
- 05
1 take away 1 leaves nothing — and a nothing at the front is not written, so the answer starts one place along.
- 06
The point in the answer comes straight down from the ones above it — it was never moved, only lined up. 13.49 − 13.17 = 0.32.