t=int(input())
while(t>0):
t=t-1
arr=input().split() #if x and n in same line!!!!
x=int(arr[0])
n=int(arr[1])
noc=x
while(noc>=n):
x=x+1
noc=noc-n+1
print(x)
dD1pbnQoaW5wdXQoKSkKd2hpbGUodD4wKToKICAgIHQ9dC0xCiAgICBhcnI9aW5wdXQoKS5zcGxpdCgpICAgI2lmIHggYW5kIG4gaW4gc2FtZSBsaW5lISEhIQogICAgeD1pbnQoYXJyWzBdKQogICAgbj1pbnQoYXJyWzFdKQogICAgbm9jPXgKICAgIHdoaWxlKG5vYz49bik6CiAgICAgICAgeD14KzEKICAgICAgICBub2M9bm9jLW4rMQogICAgcHJpbnQoeCk=