To work out 3.6 × 4, you can first ignore the decimal point: 36 × 4 = 144. Then put back the decimal point. 3.6 has one decimal place, so the answer has one decimal place too: 14.4.
Another way is to think in tenths: 3.6 is 36 tenths, and 36 tenths × 4 is 144 tenths, which is 14.4. Always check with an estimate: 3.6 × 4 is a bit less than 4 × 4 = 16.
Worked example
2.75 × 6 =
- Work out 275 × 6 = 1650.
- 2.75 has two decimal places, so the answer does too: 16.50.
Answer:16.5
Key words
- decimal place
- a digit after the decimal point
- estimate
- a rounded answer to check with
- tenths
- parts of a whole split into ten
Practise this
New questions every time.
Common Core-referenced: 5.NBT.B.7