#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
bool memBeg;
template<typename T,typename TT> void chkmin(T &x,TT y) {if(x>y) x=y;}
template<typename T,typename TT> void chkmax(T &x,TT y) {if(x<y) x=y;}
constexpr int mod=998244353;
void inc(int &x,int y) {x+=y; x-=(x>=mod)*mod;}
void dec(int &x,int y) {x-=y; x+=(x<0)*mod;}
constexpr int add(int x,int y) {return (x+y>=mod)?x+y-mod:x+y;}
constexpr int sub(int x,int y) {return (x<y)?x-y+mod:x-y;}
constexpr int quick_pow(int x,ll times,int ret=1) {
    for(;times;times>>=1,x=1ll*x*x%mod) if(times&1) ret=1ll*ret*x%mod;
    return ret;
}
bool memEn;
void fl() {
    freopen(".in","r",stdin);
    freopen(".out","w",stdout);
}
int main() {
    fprintf(stderr,"%.24lf\n",fabs(&memEn-&memBeg)/1024.0/1024.0);
    // fl();
    int _; scanf("%d",&_);
    while(_--) {
        int s,c;
        scanf("%d%d",&s,&c);
        ll ret=0ll;
        {
            int a=s/(c+1),lo=s-a*(c+1),hi=s;
            ll t=1ll*(lo+hi)*(a+1)/2*c;
            chkmax(ret,t);
        }
        {
            int tk=min(c/2,(s+1)/(c+1));
            chkmax(ret,1ll*s*(s+1)/2+1ll*c*(c-1)/2*tk-1ll*tk*(tk-1)/2*c);
        }
        printf("%lld\n",ret);
    }
    return 0;
}