Project Euler getting smallest multiple in python

If a problem is hard, trying solving a simpler version. Here, how to calculate the lowest common multiple of two numbers. If you've read any number theory book (or think about prime factors), you can do that using the greatest common divisor function (as implemented by the Euclidean algorithm).

from fractions import gcd
def lcm(a,b):
    "Calculate the lowest common multiple of two integers a and b"
    return a*b//gcd(a,b)

Observing lcm(a,b,c) ≡ lcm(lcm(a,b),c) it's simple to solve your problem with Python's reduce function

>>> from functools import reduce
>>> reduce(lcm, range(1,10+1))
2520
>>> reduce(lcm, range(1,20+1))
232792560

You are doing a brute force search, so it can get arbitrary long. You should read about LCM (least common multiple) in order to code an efficient solution.(which I believe is 232792560)

int gcd(int m, int n)
{
    int t;
    while(n!=0)
    {
        t=n;
        n=m%n;
        m=t;
    }
    return m;
}

#include<stdio.h>
int main()
{
    int i,n;
    int long long lcm=1;
    printf("Enter the range:");
    scanf("%d",&n);
    for (i=1;i<=n;i++)
    {
        lcm = (i*lcm)/gcd(i,lcm);
    }
    printf("smallest multiple : %uL",lcm);

}