#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define pii pair<ll,ll>
#define rep(i,a,b) for(ll i=(a);i<=(b);++i)
#define per(i,a,b) for(ll i=(a);i>=(b);--i)
using namespace std;
bool Mbe;
inline ll read(){
	ll x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-f;ch=getchar();}
	while(ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
	return x*f;
}
inline void write(ll x){
	if(x<0)putchar('-'),x=-x;
	if(x>9)write(x/10);
	putchar(x%10+'0');
}
const ll N=5e5+9;
ll T,S,C;
ll C1(ll x,ll y){
	return x*(x-1)/2*y-y*(y-1)/2*x;
}
ll C2(ll x,ll y){
	return x*(x-1)/2*y-y*(y+1)/2*x;
}
bool Med;
int main(){
	cerr<<fabs(&Med-&Mbe)/1048576.0<<"MB\n";
	T=read();
	while(T--){
		S=read(),C=read();
		ll k=min(C/2,S/C);
		ll ans1=C1(C,k);
		k=(S-1)/C;
		ll l=S-k*C;
		ll ans2=C2(C,k)+C*l-l*(l+1)/2;
		write(max(ans1,ans2)+S*(S+1)/2),putchar('\n');
	}
	return 0;
}