C++ :

#include <cstdio>
#include <cstring>	
#include <iostream>
#include <cmath>
using namespace std;



int main()
{
	int n,m,i;
	
	cin>>n>>m;
	printf("%d/%d=%d.",n,m,n/m);
	n%=m;
	
	for (i=1;i<=20;i++)
	{
		n*=10;
		printf("%d",n/m);
		n%=m;
		if (n*pow(10,20-i)<m) break;
		}
	printf("\n");
	
	return 0;
	}
	
	

Java :

import java.io.IOException;
import java.io.PrintWriter;
import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws IOException{
        Scanner sc=new Scanner(System.in);
        PrintWriter out=new PrintWriter(System.out);
        int n1=sc.nextInt();
        int n2=sc.nextInt();
        BigDecimal a= BigDecimal.valueOf(n1);
        BigDecimal b= BigDecimal.valueOf(n2);
        BigDecimal c=a.divide(b,20,BigDecimal.ROUND_DOWN);
        String ss=c.toString();
        out.print(n1+"/"+n2+"=");
        int count=0;
        for(int i=ss.length()-1;i>=0;i--){
            if(ss.charAt(i)=='0'){
                count++;
            }else{
                break;
            }
            }
        if(count==20){
            out.println(ss.substring(0, ss.length()-count+1));
            out.flush();
        }
       else{
           out.println(ss.substring(0, ss.length()-count));
           out.flush();
        }

        }
    }