My Strategy using digistore

I used the Part Adder to solve a two digit number. 48 + 49

I got the answer 97. So I got the answer by doing this strategy  48 + 49 = 37 + 11 + 49 = 97

I worked it out by doing this 2 digit strategy 48 + 49 = 37 +11 + 49 = 97