SOLUTION: hello sir, This is Prakash Baskaran. Is there any shortcut method to find out whether a number is prime or not?? for simple numbers it is easy, but what is I'am given a huge num,

Algebra ->  Algebra  -> Divisibility and Prime Numbers -> SOLUTION: hello sir, This is Prakash Baskaran. Is there any shortcut method to find out whether a number is prime or not?? for simple numbers it is easy, but what is I'am given a huge num,      Log On

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Question 117716: hello sir,
This is Prakash Baskaran.
Is there any shortcut method to find out whether a number is prime or not?? for simple numbers it is easy, but what is I'am given a huge num,
another condition being that, the num is not divisible by any numbers from 1-15.
Pls do reply to my mail
Prakash Baskaran
Answer by MathLover1(3376) About Me  (Show Source):
You can put this solution on YOUR website!

“Fermat's little theorem” can help you to determine whether number is prime or not. One version of the theorem states:
If +p is a prime+number and b any whole number, then b%5Ep+%96+b is a multiple of +p .
Examples:
if p+=+7 and b+=2, the theorem correctly predicts that 7 divides evenly into 2%5E7+%96+2, or 126
4%5E3+-+4+=+60 is divisible by 3
7%5E2+-+7+=+42 is divisible by 2
%28-3%29%5E7+-+%28-3%29+=+-2184 is divisible by 7

2%5E97+-+2+=+158+456+325+028+528+675+187+087+900+670 is divisible by+97