#include <bits/stdc++.h>
#define int long long 
using namespace std;

int s,c;
void solve() {
    cin>>s>>c;
    int ans=0;
    for (int x=max(1ll,s-c*(c+1)/2+1);x<=min(s,max(1ll,s-c*(c+1)/2+1)+c);x++) {
        // if (c*(c+1)/2>=s-x+1) continue;
        int res=0;
        res+=(2*s-x+2)*(x-1)/2;
        res+=c*(s-x+1)*((s-x+1)/(c+1)+1);
        res-=(0+(s-x+1)/(c+1))*((s-x+1)/(c+1)+1)/2*(c+1)*c;
        // int la=0;
        // for (int k=0;k<=(s-x+1)/(c+1);k++)
        //     la+=c*(s-x+1-k*(c+1));
        ans=max(ans,res);
    }
    cout<<ans<<"\n";
}
signed main()
{
    ios::sync_with_stdio(false);
    int t=0;cin>>t;
    while (t--) solve();
    return 0;
}