alleryCompute 47 × 53 using an identity:
A2391
B2491
C2691
D2991
Answer & Solution
Correct answer: B. 2491
47 × 53 = (50 − 3)(50 + 3) = 50² − 3² = 2500 − 9 = 2491. The (a − b)(a + b) identity makes products of numbers near a 'nice' centre very fast.
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