To determine if 81 is a prime number or a composite number, we simply look at the factors for 81.
If the factors of 81 are only 81 and 1, then we know that 81 is a prime number. Otherwise, 81 is a composite number.
To explain better, if 81 is only divisible by 1 and 81, then it is a prime number, and if 81 is divisible by more than 81 and 1, then it is a composite number.
The factors of 81 are as follows:
1, 3, 9, 27, 81
Therefore, since 81 is divisible by more than one and itself, the answer to the
question "Is 81 prime or composite?" is highlighted in blue below.
composite
Is 82 prime or composite?
OK. Now you know that 81 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.
|
|
