# Prime No.

Pawan Arora

Ranch Hand

Posts: 105

posted 7 years ago

Hi, I want to find out 10001st prime number of the site Projecteuler, and here is my programme

and I'm getting the answer as 104149. I thougth I've written my code correctly, but yet I'm getting wrong answer. Could anyone please tell me the reason of not having a right result? A small hint is enougth.

and I'm getting the answer as 104149. I thougth I've written my code correctly, but yet I'm getting wrong answer. Could anyone please tell me the reason of not having a right result? A small hint is enougth.

Campbell Ritchie

Sheriff

Posts: 49382

62

posted 7 years ago

When you get prime(25) to return

Then find out how the "Sieve of Eratosthenes" works. Far better way of working out prime numbers.

**true**, get a pencil and paper, and write 1 2 3 4 . . . 24 25. Then go through your method (a complicated bit of programming, there) and work out which numbers it will reject. You need to count the iterations of the loop carefully.Then find out how the "Sieve of Eratosthenes" works. Far better way of working out prime numbers.