You can divide whole numbers and you can work with tenths and hundredths. Dividing a decimal by a whole number is fair sharing, with tenths and hundredths shared just like ones.
Key idea
Divide as with whole numbers, and put the decimal point in the quotient straight above the point in the dividend. If the division does not come out even, write zeros after the last digit and keep going.
Why it works
Sharing $6.3$ among 3 is sharing 6 ones and 3 tenths: each person gets 2 ones and 1 tenth, $2.1$. Thinking in the smallest unit helps: $9.36$ is 936 hundredths, and $936 \div 4 = 234$ hundredths, which is $2.34$. A zero at the end, $3.4 = 3.40$, adds no value but gives you hundredths to share.
Worked examples
Worked example: Share ones and tenths
Find $6.3 \div 3$.
- 6 ones $\div 3 = 2$ ones.
- 3 tenths $\div 3 = 1$ tenth.
Answer: $2.1$
Worked example: Long division with a point
Find $9.36 \div 4$.
- $9 \div 4 = 2$ with 1 left over. Write 2, then the point above the point.
- Bring down the 3: 13 tenths. $13 \div 4 = 3$ with 1 left over.
- Bring down the 6: 16 hundredths. $16 \div 4 = 4$.
- Check: $2.34 \times 4 = 9.36$.
Answer: $2.34$
Worked example: Write a zero to keep going
Find $3.4 \div 4$.
- 4 does not go into 3 ones, so write 0 ones and the point.
- 34 tenths $\div 4 = 8$ with 2 tenths left.
- Write $3.4$ as $3.40$: the 2 tenths become 20 hundredths. $20 \div 4 = 5$.
Answer: $0.85$
Common mistake
Losing the decimal point and writing $9.36 \div 4 = 234$ or $23.4$. Check with an estimate: $9 \div 4$ is a little more than 2, so the answer is $2.34$.