Times ten
One weighing slip shows 2.5 kg of rice. Ten bags like that weigh 25 kg.
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Step 1 of 4
- 2.5 sits in the ones and tenths columns.
- Multiply by 10.
- Every digit moves one column left.
- The digits now read 25.
The rule
Multiplying by 10, 100 or 1000 moves every digit left. Each digit moves one column for each zero.
A digit one column left is worth ten times as much.
Write a zero in any column left empty. The zero keeps the other digits in their columns.
0.64 × 1000 has three zeros, so three moves. The 6 starts in the tenths and the 4 in the hundredths. The 6 moves to the hundreds. The 4 moves to the tens. The ones column is empty, so write 0. The answer is 640.
Watch out!
2.5 × 10 is not 2.50. A zero at the end changes nothing. The digits must move.