#include<bits/stdc++.h>
#define pd push_back
#define all(A) A.begin(),A.end()
#define lower_bound lb
#define ve std::vector
typedef long long ll;
typedef long long ll;
typedef __int128 Int;
typedef unsigned long long ul;
typedef long double LD;
bool FileIfstream(std::string name){
	std::ifstream f(name.c_str());
	return f.good();
}
namespace Math{
	ll QP(ll x,ll y,ll mod){ll ans=1;for(;y;y>>=1,x=x*x%mod)if(y&1)ans=ans*x%mod;return ans;}
	ll inv(ll x,ll mod){return QP(x,mod-2,mod);}
}
const int N=2e5+10;
const int mod=998244353;
void solve(){
	//don't forget to open long long
	ll S,C;std::cin>>S>>C;
	ll ans=0;
	LD A=-C/2.0,B=C/2.0+(C*C-C)/2.0,CS=S*(S+1)/2;
	LD x=std::min(-B/(2*A),LD(1.0*S/C));
	auto get=[&](ll x)->ll{
		x=std::max(x,0ll);
		return round(A*x*x+B*x+CS);
	};
	ans=S*(S+1)/2;
	ans=std::max({ans,get(ceil(x)),get(floor(x))});
	std::cout<<ans<<'\n';
}
int main(){
#ifndef ONLINE_JUDGE
	if(!FileIfstream("IO.in")){
		freopen("IO.in","w",stdout);
		return 0;
	}
	freopen("IO.in","r",stdin);
	freopen("IO.out","w",stdout);
#endif
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
	std::cout.tie(0);
	int T=1;
	std::cin>>T;
	while(T--)solve();

	return 0;
}