T = int(input())
i = 0
result = []
def sum1(D,N):
sm = 0
j = 1
while j <= N :
sm = sm + j
j = j + 1
maxRange = N * D
D = D - 1
j = (j - 1) + D
while j <= maxRange and D != 0:
sm = sm + j
j = j + 1
return sm
while i < T:
D, N = map(int,input().split())
result.append(sum1(D,N))
i = i + 1
for i in result[:]:
print ( i )
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