To determine if 1815 is a prime number or a composite number, we simply look at the factors for 1815.
If the factors of 1815 are only 1815 and 1, then we know that 1815 is a prime number. Otherwise, 1815 is a composite number.
To explain better, if 1815 is only divisible by 1 and 1815, then it is a prime number, and if 1815 is divisible by more than 1815 and 1, then it is a composite number.
The factors of 1815 are as follows:
1, 3, 5, 11, 15, 33, 55, 121, 165, 363, 605, 1815
Therefore, since 1815 is divisible by more than one and itself, the answer to the
question "Is 1815 prime or composite?" is highlighted in blue below.
composite
Is 1816 prime or composite?
OK. Now you know that 1815 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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