The rounding seconds after each stage and rounding after boost requirements are not confronting to current standards, which should be to use an approximate estimation in comparing user's and actual solutions for the split time calculation. (i.e, rounding requirement completely removed) AND ONLY the final timing diff rounded down to the nearest second

Subtract the reversed x.

The description never mention anything about reversing the x, then suddenly ask us to subtract it?

Taking the below test case as an example I can't figure out why "zero" is lower case in the solution. As the fourth index in the number it seems that it should be upper case, or if we are only to look at the number of writen out numbers, then it is the second index of that so it should be uppercase. Could someone please offer an explination as to why it is lower case in the solution?

test.assert_equals(conv(47309534), "f73zero953fourFOUR")

The tests are not testing anything.

I think that it is better to add an example in the desciption so that people will understand the question clearly.

0 is considered even and positions of numbers are not zero based.

0 is not considered even, 0 is even; no need to mention that.

I'm guessing positions of numbers are one-based? Description does not exclude the possibility they are 2-based, -1-based or 137-based. It might be clearer to specify what is, rather than, partially, what is not.