Column decimals
You learn to add, subtract and multiply decimals in columns.
How to work it out
- Line up decimal points.
- Calculate as whole numbers, bringing the decimal point straight down.
11
12.45
+3.78
16.23
12.45 + 3.78
- Line up the decimal points.
- Hundredths: 5 + 8 = 13, write 3 and carry 1.
- Tenths: 4 + 7 + 1 = 12, write 2 and carry 1.
- Ones and tens: 12 + 3 + 1 = 16.
- The answer is 16.23.
11
1245
+378
1623
More examples
8.32 − 4.57
- Line up the decimal points.
- Hundredths: 2 − 7 does not work, so exchange: 12 − 7 = 5.
- Tenths: the 3 has become 2, and 2 − 5 does not work, so exchange: 12 − 5 = 7.
- Ones: the 8 has become 7, and 7 − 4 = 3.
- The answer is 3.75.
71212
832
−457
375
3.45 × 6
- Work without the decimal point: 345 × 6 = 2070.
- 3.45 has 2 digits after the decimal point.
- Give the answer 2 as well: 20.70.
345
×6
2070