To determine if 390 is a prime number or a composite number, we simply look at the factors for 390.
If the factors of 390 are only 390 and 1, then we know that 390 is a prime number. Otherwise, 390 is a composite number.
To explain better, if 390 is only divisible by 1 and 390, then it is a prime number, and if 390 is divisible by more than 390 and 1, then it is a composite number.
The factors of 390 are as follows:
1, 2, 3, 5, 6, 10, 13, 15, 26, 30, 39, 65, 78, 130, 195, 390
Therefore, since 390 is divisible by more than one and itself, the answer to the
question "Is 390 prime or composite?" is highlighted in blue below.
composite
Is 391 prime or composite?
OK. Now you know that 390 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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