My Partner is?

• Here are several pairs of numbers.
  What value should replace the question mark?
  (1, 3); (2, 3); (3, 5); (4, 4); (5, 4); (6, 3); (7, 5); (8, 5); (9, 4); (10, ?)

Answer:
	Please enter a numerical answer (ex. 1000 or 2.033) and click GO.