To add or subtract decimals, line up the decimal points so that tenths are under tenths and hundredths under hundredths. Then add or subtract as you would with whole numbers, carrying or exchanging when needed.
If the numbers have a different number of decimal places, fill the gaps with zeros. 12.4 − 3.75 becomes 12.40 − 3.75. Put the decimal point in the answer straight below the others: 8.65.
Worked example
6.93 + 7.8 =
- Write 7.8 as 7.80 and line up the points.
- Hundredths: 3 + 0 = 3. Tenths: 9 + 8 = 17, write 7 carry 1. Ones: 6 + 7 + 1 = 14.
Answer:14.73
Key words
- decimal point
- separates wholes from parts
- line up
- put the same places under each other
- placeholder zero
- a zero added to fill an empty place
Practise this
New questions every time.
Common Core-referenced: 5.NBT.B.7