METHOD TO CHECK WHETHER A NUMBER IS A PRIME OR NOT …. ?
PRIME NUMBER : A number is greater than 1 is called a prime number, if it has only two factors, namely 1 and the number itself.
Procedure to find out the prime number:
Suppose A is given number.
Step 1: Find a whole number nearly greater than the square root of A.
K > square root(A)
Step 2: Test whether A is divisible by any prime number less than K. If yes A is not a prime number. If not, A is prime number.
Find out whether 337 is a prime number or not?
Step 1: 19 > square root (337) Prime numbers less than 19 are 2, 3, 5, 7, 11, 13, 17
(19*19=361 and 18*18=324.So,we need to find a whole number number greater than the square root of 337.As 324<337<361 we need to take 19)
Step 2: 337 is not divisible by any of them
Therefore 337 is a prime number