To determine if 78 is a prime number or a composite number, we simply look at the factors for 78.
If the factors of 78 are only 78 and 1, then we know that 78 is a prime number. Otherwise, 78 is a composite number.
To explain better, if 78 is only divisible by 1 and 78, then it is a prime number, and if 78 is divisible by more than 78 and 1, then it is a composite number.
The factors of 78 are as follows:
1, 2, 3, 6, 13, 26, 39, 78
Therefore, since 78 is divisible by more than one and itself, the answer to the
question "Is 78 prime or composite?" is highlighted in blue below.
composite
Is 79 prime or composite?
OK. Now you know that 78 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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