Can some explain that how this program works

Question

#include <iostream>
using namespace std;
int main(){

double num;double mod=1;double c=0;

cout <<"Enter a number ";
cin>>num;

for(int d=0; d<50; d++){
if(c*c>num){
c-=mod; mod/=10;}
c+=mod;
}
cout<<"Square root of "<<num <<" is "<<c<<endl;
return 0;
}

Answer 1

It iterates 50 times to approximate the square root of the user input.