To determine if 391 is a prime number or a composite number, we simply look at the factors for 391.
If the factors of 391 are only 391 and 1, then we know that 391 is a prime number. Otherwise, 391 is a composite number.
To explain better, if 391 is only divisible by 1 and 391, then it is a prime number, and if 391 is divisible by more than 391 and 1, then it is a composite number.
The factors of 391 are as follows:
1, 17, 23, 391
Therefore, since 391 is divisible by more than one and itself, the answer to the
question "Is 391 prime or composite?" is highlighted in blue below.
composite
Is 392 prime or composite?
OK. Now you know that 391 is a composite number. Use our logic above and see if
you can figure out if the next number on our list is prime or composite before you check your answer.
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