The GMAT Sample Math question is a Number Systems question and the concept covered is finding the number of factors or integral divisors of a number.
Question: How many integral divisors does the number 120 have?
- None of these
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Express the number in terms of its prime factors
120 = 23 * 3 * 5.
The three prime factors are 2, 3 and 5.
The powers of these prime factors are 3, 1 and 1 respectively.
Find the number of factors as follows
To find the number of factors / integral divisors that 120 has, increment the powers of each of the prime factors by 1 and then multiply them.
Number of factors = (3 + 1) * (1 + 1) * (1 + 1) = 4 * 2 * 2 = 16.
Choice B is the correct answer.