Which prime number comes immediately after 31?

• A. 29
• B. 31
• C. 37
• D. 41

Answer: (C)

Primes are numbers greater than 1 with no divisors other than 1 and themselves. To find the prime that comes after 31, check the subsequent numbers one by one for primality.

After 31, the next numbers are 32, 33, 34, 35, 36, and then 37. Each of the first five has a small divisor: 32 is even, 33 is divisible by 3, 34 is even, 35 is divisible by 5, and 36 is divisible by 2 and 3. So none of them are prime. The next number, 37, is not divisible by 2, 3, or 5, and since the square root of 37 is about 6, there are no other primes to test. Therefore, 37 has no divisors other than 1 and itself, making it prime. The prime that comes immediately after 31 is 37.