input: Write a python function to find pairs of numbers whose product is 10 from 1 to 10.
  assert find_pairs() == [(1, 10), (2, 5), (5, 2), (10, 1)]
output: def find_pairs():
      pairs = []
      for i in range(1, 11):
          for j in range(1, 11):
              if i * j == 10:
                  pairs.append((i, j))
      return pairs