This is a serie of ordered pairs:
(0,6), (1,2), (2,5), (3,5), (4,4), (5,5), (6,6), (7,3), (8,7), and (9,6) and this is the whole serie.
This means that every one-figure number has a corresponding number attached. Like you say 3 and I say 5. 10 is not defined in this serie so you get no answer for that.
Here is the question: What is the principle behind the pairs?
(This is perhaps an impossible question if you are not a Mega Mensa of some kind, but start asking questions about it and I answer in regular intervalls. If no questions comes, then I start giving hints after a while.)