input: Write a python function to print multiplication table up to n using nested loops.
  assert print_multiplication_table(3) == "1 x 1 = 1\t1 x 2 = 2\t1 x 3 = 3\t\n2 x 1 = 2\t2 x 2 = 4\t2 x 3 = 6\t\n3 x 1 = 3\t3 x 2 = 6\t3 x 3 = 9\t\n"
  assert print_multiplication_table(2) == "1 x 1 = 1\t1 x 2 = 2\t\n2 x 1 = 2\t2 x 2 = 4\t\n"
  assert print_multiplication_table(1) == "1 x 1 = 1\t\n"
output: def print_multiplication_table(n):
      result = ""
      for i in range(1, n+1):
          for j in range(1, n+1):
              result += f"{i} x {j} = {i*j}\t"
          result += "\n"
      return result