Speed calculation · lesson 17 of 25 · free

Decimal point jumps — Speed Calculation

Multiplying or dividing by 10, 100 or 1000 never changes the digits — only where the decimal point sits. Count the zeros: that is how many places the point jumps. Right for ×, left for ÷, and fill empty places with 0s.

The fast method

Jump the point — “one jump for each zero: right for ×, left for ÷”

  1. Count the zeros: 10 → 1 jump, 100 → 2 jumps, 1000 → 3 jumps.
  2. × moves the point right; ÷ moves it left.
  3. Run out of digits? Fill the gaps with 0s. Drop 0s at the end of a decimal: 3.40 is 3.4.

Use it for: Changing units (cm to m, g to kg, paise to rupees), metric conversions in science, and decimals in Class 5–7.

Worked example: 7.5 ÷ 1000 = 0.0075

  1. ÷ 1000: the point jumps 3 places left.
  2. 7.5 → 0.75 → 0.075 → 0.0075.

Check: 0.0075 × 1000 = 7.5 ✓

✏️ Practice

Work it out in your head or on paper, type the answer and press Check. Stuck? Press “Show me how”.

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🏁 Lesson 17 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass — and beat the clock: finish within 2 min.

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🖨️ Multiply and Divide Decimals by 10, 100, 1000 Worksheet

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