Wht are the easiest ways to figure out if a number is prime of composite

To find out if a number is prime you have to find it's factors. if the factors are only 1 and that number it's prime, if the number has other factors then it's composite. hope i helped! have a great day.

I usually start with 2 and go up the prime numbers until I get to the square root of the number and IF I haven't fond a factor by then, then I will say it is prime.

Example factors of 381
square root is roughly 19.5
Now I will see if the numbers 2, 3, 5, 7, 11, 13, 17, or 19 will go into it.  If any of them do then the number is composite, if not then it is prime.