To determine if 1989 is a prime number or a composite number, we simply look at the factors for 1989.
If the factors of 1989 are only 1989 and 1, then we know that 1989 is a prime number. Otherwise, 1989 is a composite number.
To explain better, if 1989 is only divisible by 1 and 1989, then it is a prime number, and if 1989 is divisible by more than 1989 and 1, then it is a composite number.
The factors of 1989 are as follows:
1, 3, 9, 13, 17, 39, 51, 117, 153, 221, 663, 1989
Therefore, since 1989 is divisible by more than one and itself, the answer to the
question "Is 1989 prime or composite?" is highlighted in blue below.
composite
Is 1990 prime or composite?
OK. Now you know that 1989 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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