Multiplying decimals · Usually met around P5
Decimals ×10, ×100, ×1000
Each zero moves the point one place right.
How to do it
Method
Each zero moves the point one place right
3.25 × 100 = 32.5 × 10 = 325
Another way
Move the digits
Each ×10 moves every digit up a place: 3.25 × 100 = 325
In full
×10, ×100 and ×1000 move the point one, two and three places to the right: 3.25 × 100 = 325. If you run out of digits, fill in zeros: 4.6 × 100 = 460. Zeros left at the front aren't written: 0.047 × 100 = 4.7. Another way to see it: each ×10 moves every digit up one place.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
0.86 × 10
Show the answer and working
Answer: 0.86 × 10 = 8.6
0.86 × 10: ×10 moves the point one place right, and the zeros left at the front aren't written, 0.86 × 10 = 8.6
Example 2
83.9 × 100
Show the answer and working
Answer: 83.9 × 100 = 8390
83.9 × 100: ×100 moves the point two places right, filling in zeros at the end, 83.9 × 100 = 8390
Example 3
16.1 × 100
Show the answer and working
Answer: 16.1 × 100 = 1610
16.1 × 100: ×100 moves the point two places right, filling in zeros at the end, 16.1 × 100 = 1610
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