Kata

Given a string, turn each character into its ASCII character code and join them together to create a number - let's call this number total1:

'ABC' --> 'A' = 65, 'B' = 66, 'C' = 67 --> 656667

Then replace any incidence of the number 7 with the number 1, and call this number 'total2':

total1 = 656667
              ^
total2 = 656661
              ^

Then return the difference between the sum of the digits in total1 and total2:

  (6 + 5 + 6 + 6 + 6 + 7)
- (6 + 5 + 6 + 6 + 6 + 1)
-------------------------
                       6