Simple C++ code to have fun and learn algorithm

Question

== Code founded online in Chegg, however the output is not the one that was told. It supposed to give a ounce_left of 4, but is giving an 8.

Someone knows where is the bug?

==

In this problem, our task is to find the no_of _cans needed and the no_of_ounce left over.

The formula to calculate no_of_cans needed is: ceil(amount/12).

Formula to calculate no_of_ounce needed is: 12*ceil(amount/12)-amount.

Algorithm

1. Take input amount from user.
2. Divide amount/12 and store ceil of quotient in variable cans_needed.
3. Ounce_left will be calculated as 12*cans_needed-amount.
4. Print cans_needed.
5. Print ounce_left.
6. Stop.

Now let us try to implement the above algorithm using C++.

//header files used
#include<bits/stdc++.h>
using namespace std;

int main()
{
        int amount;
        //taking input from user
        cout<<"Enter Amount in ounces:";
        cin>>amount;
        
        //finding no of cans needed 
        //if it is evenly divided by 12 then ceil(quotient)=quotient 
        //else ceil(quotient)=quotient+1
        
        int cans_needed=ceil((double)amount/12);
        
        //finding ounce_left
        int ounce_left=amount%12;
        
        cout<<"Cans Needed :"<<cans_needed<<endl; //printing cans_needed
        
        cout<<"Ounce left: "<<ounce_left<<endl;  //printing ounce_left
        
        
}