Question

a is a natural number such that a has exactly two divisors and (a + 1) has exactly three divisors. The number of divisors of a + 2 is ________.

Answer 1

a has exactly 2 divisor

∴ a must be a prime number

Let a = 3

∴ a + 1 = 4

Number of divisor of a + 2 = 3 + 2 = 5 = 2.