local t = io.read("*n")
local a, b = (function (len)
  local tb_1 = {}
  local tb_2 = {}
  for i = 1, len do
    tb_1[i] = io.read("*n")
    tb_2[i] = io.read("*n")
  end
  return tb_1, tb_2
end)(t)

for i = 1, t do
  local ans = b[i] + a[i] * b[i]
  print(ans)
end