The note
How schools teach it now
Column methods with the decimal points lined up, filling gaps with zeros (4.60 − 1.85). To multiply, children work out the whole-number fact (3 × 7 = 21), then use place value to adjust it (0.3 × 7 = 2.1).
5-minute kitchen-table activity
Use a receipt: 'A £1.35 drink and a £2.80 sandwich. What's the total? What change from £5?' (£4.15, then 85p.) Write it in columns with the points lined up.
Worked example
Work out 4.6 − 1.85.
- Line up the points and add a zero: 4.60 − 1.85.
- Hundredths: exchange 1 tenth, so 10 − 5 = 5.
- Tenths: 5 − 8 won't go, so exchange 1 one: 15 − 8 = 7.
- Ones: 3 − 1 = 2.
Answer: 2.75
Common mistakes to watch for
- Lining up the last digits instead of the decimal points.
- Thinking 0.3 × 7 = 0.21.
- Leaving out a zero placeholder, so the columns slip.
Encouragement
- Try saying
- “Line up the points and the rest falls into place.”
- Rather than
- “Decimals are just fiddly.”