too big numbers

[cool dude]

a question that i'm doing is this:

Quote:

Problem 20

n! means n × (n − 1) × ... × 3 × 2 × 1

Find the sum of the digits in the number 100!

the problem with this is that the sum is too big(unless i did something wrong) thus it keeps displaying 0. is there any way to fix that?

code:

public class Problem20 {         public static void main (String[] args){                 int n = 100;                 int total = 100;                 int sum = 0;                                 for (int i = 1; i <= 99; i++){                         total = total * (n-i);                         }                 for (int j = 1; j <= total; j++){                         sum = sum + j;                 }                 System.out.println(sum);                        } }

[wtd]

BigInteger

[cool dude]

i'm running into too many problems with BigInteger because i don't really know how to use it. i tried it and then it said i can't use operators with BigInteger i know i'm solving the question incorrectly because the answer shouldn't be this big but it doesn't really matter i'm now more interested in knowing how to use BigInteger. was there a tutorial done on BigInteger?

[codemage]

BigInteger is a class, so it doesn't work the same way that integer primitives do.

See the methods here for common operations:

http://java.sun.com/j2se/1.4.2/docs/api/java/math/BigInteger.html

[[Gandalf]]

Why link to the Java 1.4.2 documentation? Whenever possible, you should be using the most modern version of documentation/code. Here's the 5.0 documentation for BigInteger:
http://java.sun.com/j2se/1.5.0/docs/api/java/math/BigInteger.html