I enjoyed this Kata. I hope the description will be updated in C to state that low aces are possible.

Great Kata. I think a good extension to this would be to find the term number in the binomial expansion given n and the term as a string.

Thank you! I enjoyed working on this kata. I did find the description missing some formating details that extended my debugging time. For example, "0-9 Push this number onto the stack." could specify to push it to the stack as an int. I found the description available at https://esolangs.org/wiki/Befunge to be very helpful. Another helpful resource is https://tio.run/##S0pNK81LT9W1tNAtqAQz//9XslRMySnKD1fQyc/JSfVQSs7Wcfj/HwA.

'08>:1-:v v *_$.@ \n ^ _$>:^'

I had this but realized the 5 was lost in division. Cast the division as an int and it should fix it in python. In other languages you may need a data type that holds larger integers.

Thank you. I missed the quote about the lowest one.

let ? = x in an algebraic equation

so 5? = 50 + x
?? = 10x + x

47848+-?39008=-5911?0
47,848+-(100,000x + 39,008) = -(591,100 + 10x)
47,848 - 100,000x - 39,008 = -591,100 - 10x
-99,990x = -599,940
x = 6

Incorrect test case...
The solution is not 0 in this case. Consider the following interpretation:
-5?*-1=5?
let x = ? (any digit from 0-9)
-(50 + x)(-1) = 50 + x
50 + x = 50 + x // distribute the (-1)
x = x // subtract 50 on both sides
The solution could be any digit from 0-9.

I think the description would be more precise if it stated "A user's progress is 0 after reaching rank 8." in addition to stating "A user cannot progress beyond rank 8."