Games - How many games ( spoj question).

game.java

import java.util.*;
import java.lang.*;

class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner s=new Scanner(System.in);
		int num = s.nextInt();
		for(int i=0;i<num;i++){
			String input = s.next();
			if (!input.contains(".")){
				System.out.println(1);
			} else {
				String frag = input.substring(input.indexOf('.')+1);
				int number = Integer.parseInt(frag);
				int length = frag.length();
				int power = (int) Math.pow(10, length);
				int dec = power;
				while(dec%number!=0){
					dec = dec + power;
				}
				System.out.println(dec/number);
			}
		}
	}
}

Why is this approach of multiplying the decimal part till an integer is obtained, wrong?
#include<bits/stdc++.h>
using namespace std;
int main() {
int t,int_part,num;
double n,dec_part;
cin>>t;
while(t--) {
cin>>n;
num=1;
int_part=int(n10000)/10000;
dec_part=(n-int_part);
if(dec_part!=0) {
while(1) {
float temp=dec_partnum;
int int_part_temp=int(temp*10000)/10000;
double dec_part_temp=(temp-int_part_temp);
if(dec_part_temp==0)
break;
else
num++;
}
}
cout<<num<<endl;
}
}