Nested Function Fun: GMAT Question of the Day

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Nested Function Fun: GMAT Question of the Day

Problem Solving: GMAT Question of the Day
Explanation
To solve nested functions, work from the inside out. First, to find f(250), factor 250:

250 = 2 × 5 × 5 × 5

The sum of the unique primes is 2 + 5 = 7 = f(250) Next, f(f(250)) = f(7)
7 only has one prime factor: 7, so the sum is 7.

The correct answer is B.