10 + 7 = 17
2 + 17 = 19
5 + 6 = 11
19 + 11 = 30
50 + 30 = 80

50 x 10 = 500
5 x 500 = 2500
2 + 2500 = 2502
6 x 2502 = 15012
7 + 15012 = 15019

5 - 2 = 3
10 + 7 = 17
6 x 50 = 300
300 - 17 = 283
283 + 3 = 286