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Project Euler #20: Factorial digit sum

Question
n! means n × (n − 1) × ... × 3 × 2 × 1
For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800,
and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.
Find the sum of the digits in the number 100!

Answer : 648

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Solution

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import java.io.*;
import java.util.*;
import java.math.BigInteger;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner scanner= new Scanner(System.in);
        int T= scanner.nextInt();
        for(int a0= 0; a0< T; a0++){
            BigInteger N= scanner.nextBigInteger();
            if(N.compareTo(BigInteger.valueOf(0))== 0){
                System.out.println("1");
                continue;
            }
            BigInteger sum= new BigInteger("0");
            BigInteger fact= N;
            while(N.compareTo(BigInteger.valueOf(1))== 1){
                fact= fact.multiply(N.subtract(BigInteger.valueOf(1)));
                N= N.subtract(BigInteger.valueOf(1));
            }
            while(fact.compareTo(BigInteger.valueOf(0))== 1){
                BigInteger temp= fact.mod(BigInteger.valueOf(10));
                sum= sum.add(temp);
                fact= fact.divide(BigInteger.valueOf(10));
            }
            System.out.println(sum);
        }
    }
}
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