#include <iostream>
#include <iomanip>
using namespace std;

int main(){
double n, gal,liters;
    for(n=0;n<=9;n++){
        cout<<"Enter amount of gallons: ";
        cin>>gal;
        liters = gal*3.785;
        cout<<gal<<" gallons in liters is "<<liters<<"\n\n";}

return 0;}

... bits of code
cin >> gal;

if(cin.fail()) {
   // take some action;
}

... bits of code