Curious Number

Computer Science Level 3

145 is a curious number, as $1!$ $+$ $4!$ $+$ $5!$ $=$ $1 + 24 + 120 = 145$ .

Find the sum of all numbers which are equal to the sum of the factorial of their digits that are less than 1 million.

Note: $1! = 1$ and $2! = 2$ are not considered sums and they are not included.

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The answer is 40730.

1 solution

Rishabh Deep Singh
May 31, 2017

public class main {
    public static int last_digit(int n){
        n=n%10;
        return n;
    }
    public static int factorial(int n){
        if (n == 0)
            return 1;
        else
            return(n * factorial(n-1));
    }
    public static void main(String[] args){
        int n,Total_sum=0;
        for (int i=3;i<1_000_000;i++) {
            n=i;
            int sum=0;
            while (n > 0) {
                int temp_last = last_digit(n);
                int temp_fact = factorial(temp_last);
                n = (n - (last_digit(n))) / 10;
                sum += temp_fact;
            }
            if (sum == i) {
                Total_sum+=i;
                System.out.println("The Number " + i + " is a curious number.");
            }
        }
        System.out.println("The the of all Curious Numbers is : "+Total_sum);
    }
}

$\text { It never can be a solution because the solution must not be a script of java, c++, etc. }$

. . - 3 months, 1 week ago

Curious Number

The answer is 40730.

1 solution

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