Try dividing by some numbers. The larger the number, the more numbers you have to divide by. It is enough to test division by 2, and all the odd numbers up to the square root of the number.
For very large numbers, this is not efficient. There are more efficient methods, but they are also more difficult to understand.
Chat with our AI personalities
You can tell it's a composite number if it can only be multiplied by 1 and itself.
You cannot. If a number is even - other than 2 - then it is a composite number. However, if it is odd, it is not easily possible to tell whether it is prime or composite.
it is a composite number because you can tell from the 8 that it is an even number, and even numbers can always be divided.
you cant
A good way to instantly tell if a number is prime or composite is to learn some tricks to tell if a number divides by certain numbers. For instance, if a number is even, we know it is composite as it must be divisible by 2. If a number ends in 0 or 5, then it also cannot be prime as it would be divisible by 5. In this case, the number ends in 5, so we can tell it must be composite and cannot be prime.
Prime numbers have two factors. Composite numbers have more than two.