How do you find which is prime and composite number?

Answer 1

if a number is divisible by any other number other than the number itself and 1 , then it is a composite number and if not divisible by any other number other than 1 or the number itself , then it is a Prime number . to find it out easyly , take the 1st prime number , that is 2 and eliminate all multiples of 2 from composite number list , then take the next number which is left . i.e. 3 , remove all multiples of 3 and then take the next number left that is 5 and do the same then 7 , then 11 , then 13 , then 17 , then 19 , then 23 , thne 29 , then 31 , then 37 , then 41 , then 47 , then 49 and so on