TO CHECK WHETHER A NUMBER IS PRIME OR NOT

         SHORT CUT PROCESS
TO CHECK WHETHER A NUMBER
            IS PRIME OR NOT

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** To check whether a number N is prime, adopt the following process

A) Take the square root of the number.

B) Round of the square root to the immediately lower integer. Call this number z.
For example if you have to check for 190, its square root will be 13... Hence, the value of z, is this will be 13.

C) Check for Divisibility of the number N by all prime numbers below z. If there is no prime number below the value of z which divides N then the number N will be prime.

TO ILLUSTRATE ::-

The value of √239 lies 15 and 16. Hence, take the value of z as 16.
Prime numbers less than 16 are 2,3,5,7,11and13,
239 is not Divisible by any of these.
Hence you can conclude that 239 is a prime number.

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