GMy GYM MathMOE-aligned Primary Maths
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P5 · Topic

Decimals

Line up place values. Count decimal places carefully.

Big Idea
Line up place values. Count decimal places carefully.
0.301
Place the value between two known points.
Key points
  1. 1For ×, count total decimal places in both numbers.
  2. 2For ÷ by a decimal, multiply both numbers by 10, 100…
  3. 3Estimate first: 4.8 × 2.5 ≈ 5 × 2.5 = 12.5.
  4. 4Keep units consistent (cm, m, L) throughout.
Worked example
  1. 148 × 25 = 1200.
  2. 2Total decimal places: 1 + 1 = 2.
  3. 3Answer = 12.00 = 12.
Answer: 12
GYM Teaching Tip
Write zeros to keep decimal places aligned when subtracting.
See the question behind this example
Find 4.8 × 2.5.