To determine if 1990 is a prime number or a composite number, we simply look at the factors for 1990.
If the factors of 1990 are only 1990 and 1, then we know that 1990 is a prime number. Otherwise, 1990 is a composite number.
To explain better, if 1990 is only divisible by 1 and 1990, then it is a prime number, and if 1990 is divisible by more than 1990 and 1, then it is a composite number.
The factors of 1990 are as follows:
1, 2, 5, 10, 199, 398, 995, 1990
Therefore, since 1990 is divisible by more than one and itself, the answer to the
question "Is 1990 prime or composite?" is highlighted in blue below.
composite
Is 1991 prime or composite?
OK. Now you know that 1990 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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