Prime number check.

Prime numbers are those numbers which are only divisible by
one and itself.

1,35,7,11,13,17 and so on……..

For small numbers it is easy to say whether number is Prime
number or not.

But for large number like 1189 it is quite difficult to check
its prime number test

But here is the trick that can check Prime number test within
fraction of seconds.

If the number contains 2 or multiple of 2 at ones place it is
not a prime number.

Like 2782, 1322, 1238, 9876 etc.

Whatever is the number use this trick.

Let the number be 89

Divide this number by 8 and then 9, 8+9=17 and 7+1=8

First step = 89/8
not divisible

Second step = 89/9 not divisible

3

^{rd}step = 89/17 not divisible
Final step =89/8
not divisible

So the number is Prime number.

Now check number 139

**Important Note**If number contains one at any position doesn’t check the number for one.

First step =139/3
not divisible

Second Step = 139/9
not divisible

Third step = 139/13 not divisible

Final step = 139/4
not divisible.

So the number is Prime number.

Now check the number 453

First step = 453/4
not divisible

Second Step = 453/5 not divisible

Third step = 453/3
= 151.

Since it is divisible so the number is not a Prime number.

This tricks works for a large number also. It will not take
your much time to practice this trick.

That doesn't work for all primes........Only some of them

ReplyDeletetry it with 187...

ReplyDelete