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

int s,c,ans;
int check(int x) {
    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;
    ans=max(ans,res);
    return res;
}
void solve() {
    cin>>s>>c;ans=0;
    int l=max(1ll,s-c*(c+1)/2+1),r=min(s,max(1ll,s-c*(c+1)/2+1)+c+1-max(1ll,s-c*(c+1)/2+1)%(c+1));
    while (l<=r) {
        int Mid=(l+r)>>1;
        if (check(Mid)<check(Mid+1)) l=Mid+1;
        else r=Mid-1;
    }

    l=max(1ll,s-c*(c+1)/2+1)+c+1-max(1ll,s-c*(c+1)/2+1)%(c+1),r=min(s,max(1ll,s-c*(c+1)/2+1)+c);
    while (l<=r) {
        int Mid=(l+r)>>1;
        if (check(Mid)<check(Mid+1)) l=Mid+1;
        else r=Mid-1;
    }

    // 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++) {
    //     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;
    //     ans=max(ans,res);
    // }
    cout<<ans<<"\n";
}
signed main()
{
    ios::sync_with_stdio(false);
    int t=0;cin>>t;
    while (t--) solve();
    return 0;
}