Decimals plus and minus
You learn to add and subtract decimals by thinking of them as hundredths.
How to work it out
- Write numbers as hundredths: 0.25 is 25 hundredths.
- Calculate with integers.
- Convert back: 75 hundredths is 0.75.
0.25 + 0.5
- Write them as hundredths: 25 and 50.
- Work it out: 25 + 50 = 75.
- Put it back: 75 hundredths is 0.75.
More examples
1 − 0.55
- Write them as hundredths: 100 and 55.
- Work it out: 100 − 55 = 45.
- Put it back: 45 hundredths is 0.45.
1.5 + 2.5
- Write them as hundredths: 150 and 250.
- Work it out: 150 + 250 = 400.
- Put it back: 400 hundredths is 4.