#include<iostream>
 
#include<iomanip>
 
using namespace std;
 
	double prod(double m, double n){
 
	if(n==0)
       return 0;
    else
       return m + prod(m,n-1); 
 
      // return n*m;
 
       }
int main()
	{
	    int n;
	cin>>n;
    double a[n],b[n];
    double r[n];
    for(int i=0;i<n;i++){
      cin>>a[i]>>b[i];
      r[i]=prod(a[i],b[i]);
    }
	  for(int i=0;i<n;i++){
            cout.setf(ios::fixed);
	  cout<<setprecision(0)<<r[i]<<endl;
	  }
 
	  return 0;
	}
 

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NQo0IDIKMTIzIDQzCjMyNCAzNDIKMCAxMgo5OTk5IDEyMzQ1

5
4 2
123 43
324 342
0 12
9999 12345