for anyone who's wondering:
Steps 2, 3 and 4 are a three step process to "create a multiple of 9", and every multiple of 9 (up to 90) has a digit sum of 9.
(Actually, step 2 and 4 are; step 3 is just there to make it less obvious - and adding 3 to what is currently a multiple of 3 doesn't change that fact)
Basically, with your initial number being "9" you'd have:
1: 9
2: 9*3
3: (9*3)+3 ➡ which is the same as 10*3; similarly, when picking "3"; (3*3)+3 would be 4*3
4: 10*3*3 = 10*9 = 90
5: 9+0 = 9; the other possibilites are 18, 27, 36, ... and so on
#nofunallowed
