//Author: Kevin
#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
#define ll long long
#define ull unsigned ll
#define pb emplace_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define inf 0x3f3f3f3f
#define pii pair<int,int>
#define lb(v,x) (int)(lower_bound(ALL(v),x)-v.begin())
#define ub(v,x) (int)(upper_bound(ALL(v),x)-v.begin())
#define uni(v) v.resize(unique(ALL(v))-v.begin())
#define longer __int128_t
void die(string S){puts(S.c_str());exit(0);}
ll calc(int l,int r)
{
	return 1ll*r*(r+1)/2-1ll*l*(l-1)/2;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int t;
	cin>>t;
	while(t--)
	{
		int n,c;
		cin>>n>>c;
		ll lim=1ll*c*c*c;
		ll ans=0;
		if(lim<n)
		{
			ans+=calc(lim+1,n);
			n=lim;
		}
		while(n>0)
		{
			ll val1=calc(max(0,n-c),n);
			ll val2=1ll*n*c;
			ll cnt=(n+c)/(c+1);
			if(val1<val2&&n<cnt*c)
			{
				ans+=val2;
				n-=c+1;
				continue;
			}
			ans+=n;
			n--;
		}
		cout<<ans<<'\n';
	}
	return 0;
}