Yours is also a good absurd solution

I am not a fan of how this is structured, I solved this assuming that the input was the actual value not inputting characters. This kata should be about drawing a triangle and not parsing input.
Also why don't the expected outputs have newlines? When outputting text it should end with a newline.

Why do you have the ++> at the start? I don't see it doing anything

Oh I could have just added the second number twice, always overcomplicate things

Just noticed that I forgot to update the cell numbers, I did have null being first but then I realised I can't use it so I removed it and now my arrays start at 1

Oh I was an idiot, I wrote this using 5 numbers and didn't consider that arrays with more than 5 numbers could make the gap bigger than 1, I'm going to raise the number intervals to .2 which will solve this

Because when working with money you round values.

I think you miss my point entirely, I'm not arguing that the kata says that 1500.129 should become "1,500.12" - I'm arguing that it shouldn't require that, numbers should be rounded.

Why would 1500.129 become "1,500.12" and not "1,500.13"?
Shouldn't it round numbers and not just cut off digits ignoring rounding?

(F#)

I'm getting the error which is not related to my code and the wrapper for the question

/home/codewarrior/program.fsx(17,23): error FS0039: The value, constructor, namespace or type 'Concat' is not defined. Maybe you want one of the following:
   concat

No matter what it throws this error, it's a problem with the question (I'm not using concat)

This shows up when attempting and not when running sample tests

I am dyslexic and chrome didn't flag it, get over it.

That was horribly explained, the description should say something along the lines of "find the number of occurances of digit d in all numbers from 0 to n squared"

Using a cache just moves the problem, I'm not sure about the real world usage of needing fibonacci numbers on demand but this will be a little slower than a known number but way faster than an unknown number