Factorial in C

#include<stdio.h>

int factorial(int num) {
    int a;
    int result=1;
    for(a=1; a<=num; a++) {
        result*=a;
    }
    return result;
}

int main(){
    int i;
    for(i=1; i<=6; i++) {
        int k = factorial(i);
        printf("%d factorial is %d\n", i, k);
    }

    anykey();
    return 0;
}