Lesson 9 of 15
Dividing by a decimal
Show on a big screenA jug holds 2.4 litres. A cup holds 0.3 litres. How many cups can you fill?
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Step 1 of 4
- The jug holds 2.4 litres. Cut it into 24 blocks of 0.1 litre.
- One cup is 0.3 litre. That is 3 blocks.
- In blocks, the jug is 24 and a cup is 3. So 2.4 ÷ 0.3 = 24 ÷ 3.
- 24 blocks make 8 cups of 3 blocks. So 2.4 ÷ 0.3 = 8.
The rule
You can fill 8 cups. Check: 8 × 0.3 = 2.4.
The divisor is the number you divide by. The dividend is the number being divided.
Multiply both numbers by the same 10, 100 or 1000. The answer does not change.
Pick the number that makes the divisor whole. For 2.4 ÷ 0.3, multiply both by 10. That gives 24 ÷ 3 = 8.
Counting in small blocks changes the numbers. It does not change how many cups fit.
| Sum | Multiply both by | New sum | Answer |
|---|---|---|---|
| 9.1 ÷ 0.7 | 10 | 91 ÷ 7 | 13 |
| 5.4 ÷ 0.06 | 100 | 540 ÷ 6 | 90 |
| 4.5 ÷ 0.4 | 10 | 45 ÷ 4 | 11.25 |
0.06 has 2 places, so multiply by 100. 5.4 becomes 540.
45 ÷ 4 does not divide exactly. Finish it with long division. 4 × 11 = 44, which leaves 1. Sharing that 1 gives 0.25 more, so 11.25.
Try the lab to finish this lesson.