For anyone else who decides to play, the confusion for me was the alignment of the digital root numbers (89, 17, 8). In the following, the transitions between 17 and 8 are, 1 and off(=2), and 7 and 8(=3). I had incorrectly done it the opposite way, 1 and 8, and 7 and off.

 Code:
  Sam   Max
  7+6  (7+6)*2  
89
  5+2  (2+4)*2
17
  2+3  (7)*2
 8
    7
  =32   =52   result: 20


Hope this helps.