import sys
from math import ceil
# import bisect
# from collections import deque

Ri = lambda : [int(x) for x in sys.stdin.readline().split()]
ri = lambda : sys.stdin.readline().strip()
 
def input(): return sys.stdin.readline().strip()
def list2d(a, b, c): return [[c] * b for i in range(a)]
def list3d(a, b, c, d): return [[[d] * c for j in range(b)] for i in range(a)]
def list4d(a, b, c, d, e): return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]
def ceil(x, y=1): return int(-(-x // y))
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]
def Yes(): print('Yes')
def No(): print('No')
def YES(): print('YES')
def NO(): print('NO')
INF = 10 ** 18
MOD = 10**9+7

for _ in range(int(ri())):
    n,k = Ri()
    z = n-k
    o = k+1
    each  = z//o
    rem = z%o
    tot=  0
    ite = rem
    # while(ite > 0):
    tot+=  rem*(each+1)*(each+2)//2
        
    tot = tot + (o-rem)*each*(each+1)//2
    # print(tot)
    print(n*(n+1)//2 - tot)

                
