C :

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<ctype.h>
#include<math.h>
int main(){
	int  a,b,n;
	scanf("%d%d%d",&a,&b,&n);
	printf("%d%s",a/b,".");
	while(n!=0){
		a = a%b*10;
		printf("%d",a/b);
		n--;
	}
	return 0;
}

C++ :

#include <iostream>
using namespace std;
 
int main(){
    int a,b,k,n,i;
    cin>>a>>b>>n;
    cout<<a/b<<'.';
    k=a%b;
    for(i=0;i<n;i++){
        k=k*10;
        cout<<k/b;
        k=k%b;
    }
}

Python :

sr=input().split()
x1=int(sr[0])
x2=int(sr[1])
n=int(sr[2])
zhensu=x1//x2
s=str(zhensu)+"."
yushu=x1%x2
for i in range(n):
    div1=yushu*10
    s=s+str(div1//x2)
    yushu=div1%x2
print(s)