Identify which of the following numbers is not a prime number. (Hint: you don't need to calculate these values.)

Answer Choices

Correct answer marked below

7!-1

7!-17

7!+11

7!+28

Correct

7!+59

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Explanation

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Official Explanation

Official

A prime number is defined as having exactly two distinct positive divisors: 1 and itself. Without performing calculations, we cannot definitively determine if 7!-1 or 7!+59 are prime. However, we can conclude that 7!+28 is not prime. This is because 7!+28 can be expressed as…

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Comments

PusanFeb 2, 2024

thanks for taking time to upload it!

JJul 22, 2024

thanks for taking time to upload it!

What this question tests

What it tests

Your command of divisibility, primes, factors, parity, and how the GMAT tests properties of integers.

Common trap

Forgetting that 1 is not prime, that 0 is divisible by every integer, or that negative numbers flip your assumptions.