GCSE Maths Practice: decimals

Question 3 of 10

This foundation GCSE Maths question helps you practise multiplying decimals by whole numbers. It’s an essential skill used in money, measurement, and scaling problems.

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\( \begin{array}{l}\textbf{Calculate } 0.6 \times 3.\end{array} \)

Choose one option:

When multiplying by whole numbers, count the total number of decimal places in the original decimal and move the decimal point the same number of places to the left in your final answer.

Multiplying Decimals by Whole Numbers

Multiplying a decimal by a whole number follows the same pattern as multiplying whole numbers. The only difference is placing the decimal point correctly at the end. You can think of decimals as fractions out of 10, 100, or 1000 — so each multiplication must account for the place value.

Step-by-Step Method

  1. Ignore the decimal point and multiply the numbers as if they were whole.
  2. Count how many digits are after the decimal in the original number.
  3. Place the decimal point in the result so it has the same number of decimal places.
  4. Check if your answer is reasonable — multiplication by a number greater than 1 should make the value larger.

Worked Examples

Example 1: 0.7 × 5 = ?
7 × 5 = 35 → one decimal place → 3.5.

Example 2: 0.25 × 4 = ?
25 × 4 = 100 → two decimal places → 1.00.

Example 3: 1.2 × 3 = ?
12 × 3 = 36 → one decimal place → 3.6.

Example 4: 0.09 × 6 = ?
9 × 6 = 54 → two decimal places → 0.54.

Common Mistakes

  • Forgetting to replace the decimal: Always return the decimal point to the correct position after multiplying.
  • Assuming the decimal point stays in the same place: It moves depending on the number of decimal digits in the factors.
  • Incorrect estimation: Check your answer’s size — 0.6 × 3 must be smaller than 3 but greater than 0.6.

Real-Life Applications

Multiplying decimals by whole numbers is essential for practical problems. For example:
• Finding the cost of 3 items at £0.60 each → £1.80.
• Scaling a recipe: 0.6 litres × 3 = 1.8 litres.
• Calculating distance or speed: 0.6 km × 3 laps = 1.8 km total.

This skill builds fluency for percentage increases, unit conversions, and proportional reasoning.

FAQs

1. How do I know where the decimal goes?
Count decimal places from the original decimal — one in 0.6 — so move the decimal one place from the right in your answer.

2. Does multiplying by 10, 100, or 1000 work the same?
Yes, but in those cases, you simply move the decimal right without doing extra multiplication.

3. Can I estimate first?
Yes, estimating helps check your accuracy: 0.6 × 3 ≈ 0.5 × 3 = 1.5, so 1.8 makes sense.

Study Tip

Write out decimal multiplications in full to spot patterns. Try these quick ones: 0.8 × 2, 0.25 × 8, 1.5 × 6. Practice estimating first, then calculating precisely to confirm your results.

Mastering multiplication with decimals will make you faster and more accurate in GCSE exam questions involving money, measurement, and proportional reasoning.