To determine if 420 is a prime number or a composite number, we simply look at the factors for 420.
If the factors of 420 are only 420 and 1, then we know that 420 is a prime number. Otherwise, 420 is a composite number.
To explain better, if 420 is only divisible by 1 and 420, then it is a prime number, and if 420 is divisible by more than 420 and 1, then it is a composite number.
The factors of 420 are as follows:
1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210, 420
Therefore, since 420 is divisible by more than one and itself, the answer to the
question "Is 420 prime or composite?" is highlighted in blue below.
composite
Is 421 prime or composite?
OK. Now you know that 420 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.
|
|
