Quantitative Aptitude • Number System & SimplificationHard
How many factors (divisors) does 1,800 have, including 1 and the number itself?
A. 36✓ Correct Answer
B. 7
C. 10
D. 34
💡 Solution & Explanation
Write the number as a product of primes: 1,800 = 2^3 × 3^2 × 5^2. A factor can use each prime from power 0 up to its full power, so the number of factors = (3 + 1) × (2 + 1) × (2 + 1) = 36. Multiplying (exponent + 1) for each prime is much faster than listing every factor.
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