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prime number

 
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prime number
anis_ahmad
18 May, 2008 - 08:26 AM
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I am trying to check the given number is prime or not
exactly i could not get logic.
prime number is divisible by 1 or number itself. but i am unable to find the logic to chek number is prime or not
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homemade-jam
RE: Prime Number
18 May, 2008 - 08:55 AM
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Anis,

What you wanna do is have your code take the input from the user; square root it (as you will not have to divide by the numbers below the square root to prove whether it is prime) and then, beginning at 2 find the modulus (remainder) of your users input divided by all numbers upto the square root.

If this modulus is 0 then the number is not prime (it divides cleanly).

If the modulus is not prime then increment the divisor by one.

Continue the process until the divisor is equal to the square root - if none of the divisions gave a modulus of 0 then the number is prime.

Jam
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