（Problem 5）Smallest multiple

2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.

What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?

#include <stdio.h>#include <string.h>#include <ctype.h>#include <math.h>  #define N 20  int gcd(int a, int b){  if(b==0)    return a;  else    return gcd(b,a%b);}  int lcm(int a, int b){  return a/(gcd(a,b))*b;}    void solve(){   int i,s=2;   for(i=3; i<=N; i++)   {      s=lcm(s,i);   }   printf("%d\n",s);}  int main(){  solve();  return 0;}

Answer:

232792560