Standard Mathematics Primary 4 Decimals

A bottle of cooking oil at NTUC Fairprice is 0.45 ℓ. Express 0.45 as a fraction in its simplest form.

A 2/5
B 9/10
C 9/20
D 45/100
Show Worked Solution

Worked Solution

Step 1: Write the decimal as a fraction using place value. 0.45 = 45 hundredths = 45/100 Step 2: Find the GCD of 45 and 100. Factors of 45: 1, 3, 5, 9, 15, 45 Factors of 100: 1, 2, 4, 5, 10, 20, 25, 50, 100 GCD = 5 Step 3: Simplify by dividing numerator and denominator by 5. 45 ÷ 5 = 9 100 ÷ 5 = 20 → 9/20 Step 4: Verify that 9/20 is in simplest form. GCD(9, 20) = 1 ✓ (9 = 3² ; 20 = 4 × 5 — no common factor) Step 5: Check by converting back. 9 ÷ 20 = 0.45 ✓ Answer: 9/20 Answer: 9/20

Correct answer: 9/20

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