01 What is the HCF of (20) and (30) using prime factorisation?
Answer and explanation
Correct answer: B. (10)
Explanation: Step 1: (20=2^2\times5) and (30=2\times3\times5). Step 2: The common prime factors are (2) and (5) with smaller powers (2) and (5). Step 3: (2\times5=10), so the HCF is (10).