Q:

Not really addition

1 + 2 = 3
1 + 4 = 3
16 + 4 = 11
4 + 4 = 7
5 + 4 = 6
5 + 2 = 10
6 + 2 = 10
2 + 2 = 7
8 + 10 = 5
4 + 10 = 4
5 + 10 = 4
3 + 10 = 5
81 + 7 = ?

Hint

 $10 + 1 \ne 1 + 10$

Hint 2

 The number four

What is the pattern? What is 81 + 7? How are the results calculated?

A:

Answer:

 81+7= 11
 81's base 7 representation is 144. Which is onefourfour, which is 11 letters long.
 81-49 = 32  (1) ->3
 32-28 = 4   (4) ->4
 4 = 4 (4) - > 4
 3+4+4 = 11

Explanation:

 take the first number, put it in the base of the second number, and count the number of letters in the representation.  

How I got it:

 The ? + 10 = ? numbers gave it away for me. 8 is 5 letters, 4 is 4 letters, 5 is 4 letters, 3 is 5 letters.

