What is a decimal?
A decimal is another way to show parts of a whole, just like a fraction. The decimal point ( . ) separates the whole number from the parts. In 0.7, the 7 is in the tenths place, so 0.7 means 7 tenths. We read it as "zero point seven".
Key idea
One tenth is written 0.1 and means 1/10. One hundredth is written 0.01 and means 1/100.
Adding and comparing decimals
Adding decimals is like adding whole numbers, but you must be careful with the point.
- Line up the decimal points.
- Add the tenths, then the whole numbers.
- To compare, look at the tenths first.
Worked example
Add 0.5 + 0.3.
0.5 means 5 tenths and 0.3 means 3 tenths. Together that is 5 + 3 = 8 tenths, which is 0.8. The decimal point stays in the same place.
Remember
- The first place after the point is tenths.
- The second place after the point is hundredths.
- 0.5 is the same as one half.