#include<cstdio>
#include<iostream>
#define db double
#define pc putchar
#define ll long long
#define Tp template<typename _T>
Tp _T mabs(_T a){ return a<0?-a:a; }
Tp _T mmax(_T a,_T b){ return a<b?b:a; }
Tp _T mmin(_T a,_T b){ return a<b?a:b; }
Tp void mswap(_T &a,_T &b){ _T t=a; a=b; b=t; return; }
using namespace std;
struct IO{
	char buf[1<<21],*p1,*p2;
	char gc(){ return p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++; }
	IO & operator >> (char &x){ x=gc(); while(x=='\r'||x=='\n'||x==' ') x=gc(); return *this; }
	Tp IO & operator >> (_T &x){
		x=0; char c=gc(); bool f=0; while(c<'0'||c>'9'){ if(c=='-') f^=1; c=gc(); }
		while('0'<=c&&c<='9') x=(x<<1)+(x<<3)+(c^48),c=gc(); f?x=-x:0; return *this;
	}
	int st[39],top;
	IO & operator << (char x) { pc(x); return *this; }
	Tp IO & operator << (_T x){
		if(x<0) x=-x,pc('-'); if(x==0){ pc('0'); return *this; }
		top=0; while(x) st[++top]=x%10,x/=10;
		while(top--) pc(st[top+1]+48); return *this;
	}
}fin;
#define maxn
ll s,c;
ll js(ll x){
	if(!x) return -1;
	ll k,l,ans;
	ans=x*c;
	k=(mmin(c*(c+1)/2,s)-x)/(c+1);
	l=k*(c+1)+x;
	ans+=(s+l+1)*(s-l)/2;
	ans+=(l+x+c+1)*k/2*c;
	return ans;
}
void work(){
	fin>>s>>c; if(c==1){ fin<<s*(s+1)/2<<'\n'; return; }
	if(s<=c){ fin<<c*s<<'\n'; return; }
	int i; ll ans=mmax(mmax(js(c),js(c-1)),js(s%(c+1)));
//	for(i=1;i<c;i++){
//		//fin<<i<<' '<<js(i)<<'\n';
//		ans=mmax(ans,js(i));
//	}
//	int l=1,r=c,lm,rm; ll ans=js(c-1);
//	while(l+10<r){
//		lm=(l+l+r)/3; rm=(l+r+r)/3;
//		if(js(lm)<js(rm)) l=lm; else r=rm;
//	}
//	while(l<=r) ans=mmax(ans,js(l)),l++;
	fin<<ans<<'\n';
}
int main(){
#ifdef LOCAL
	freopen("1.in","r",stdin);
	//freopen(".out","w",stdout);
#endif
	int T; fin>>T; while(T--) work(); return 0;
}