t=int(input())
while(t>0):
t=t-1
arr=input().split()
x=int(arr[0])
n=int(arr[1])
noc=x
while(noc>=n):
x=x+int(int(noc)/int(n));
noc=int(int(noc)/int(n))+int(noc)%n;
print(int(x))
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