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

Write a program which is smallest positive number that is evenly divisible by all of the numbers from 1 to 20 in C

#include<stdio.h>
#include<conio.h>
int main()
{
int num=20,flag=0;

while(flag==0)
{
    if ((num%2)==0&&(num%3)==0&&(num%4)==0&&(num%5)==0&&(num%6)==0
    && (num%7)==0&&(num%8)==0&&(num%9)==0&&(num%10)==0&&(num%11)==0&&(num%12)==0
    && (num%13)==0&&(num%14)==0&&(num%15)==0&&(num%16)==0&&(num%17)==0&&(num%18)==0
    && (num%19)==0&&(num%20)==0)
    {
        flag=1;
        printf("%d",num);
    }
    num++;
}
}