Using prime factorisation, √324 equals:
A12
B18
C21
D24
Answer & Solution
Correct answer: B. 18
324 = 2² × 3⁴ = (2 × 3²)² = (2 × 9)² = 18². So √324 = 18. (Pairs of primes give the square root: take one factor from each pair.)
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