A Peek Beyond the Point

Decimals continue place value to the right of the point: tenths, hundredths and thousandths. Compare, add and subtract them by lining up the points.

Key ideas

• Each place is one tenth of the place to its left: 0.1 = 1/10, 0.01 = 1/100, 0.001 = 1/1000.
• Zeros at the end after the point do not change the value: 2.5 = 2.50 = 2.500.
• To compare decimals, compare the whole parts first, then the tenths, then the hundredths.
• To add or subtract, line up the decimal points and fill gaps with zeros.
• Measures use decimals: 2 m 35 cm = 2.35 m and 1 kg 250 g = 1.25 kg.

Remember

Watch out

• Thinking 0.25 is bigger than 0.3 because 25 is bigger than 3.
• Lining up the last digits instead of the decimal points.
• Writing 2 m 5 cm as 2.5 m (it is 2.05 m).

Worked example