Learn the Method
1× 10: slide one place.
Every digit moves one column left. 3.45 → 34.5.
2× 100: slide two places.
Two columns left. 3.45 → 345.
3× 1000: slide three places.
Three columns left — pad with zeros if you run out of digits. 0.7 → 700.
Worked Example
Work these out.
Watch Out! Common Mistakes
Wrong! Adding a zero after a decimal changes nothing. The digits must move: 34.5.
Wrong! ×100 means two places: 2.6 → 260.
Wrong! Multiplying makes the number bigger — digits slide left (point appears to move right).
⬇ Cheat Sheet
- ×10 → digits slide 1 place left.
- ×100 → 2 places. ×1000 → 3 places.
- Pad with zeros if you run out of digits.
- Multiplying by 10/100/1000 always makes the number bigger.
📖 Continue Your Journey
Quick summary
- ×10 slides every digit one place left; ×100 two places; ×1000 three.
- 'Adding a zero' is the classic wrong rule — 3.45 × 10 is 34.5, not 3.450.
- Pad with zeros when digits run out: 0.7 × 1000 = 700.
- The answer is always bigger when multiplying by 10, 100 or 1000.
Frequently asked questions
How do you multiply a decimal by 10?
Move every digit one place to the left (the decimal point appears to hop one place right): 3.45 × 10 = 34.5.
Why is 'add a zero' the wrong rule?
It works for whole numbers by accident, but fails for decimals: 3.45 with a zero added is 3.450 — exactly the same value. The real rule is that digits move up the place-value columns.
What is 0.7 × 1000?
700. The 7 slides three places left, and zeros fill the empty ones and tens columns.
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