@emilmoe That depends on your understanding of maths. If you're working in a project with multiple people - hailing from multiple backgrounds then you will see such naming conventions as n, i, x. I will also say that associating names to the variables just based on the first letter is arbitrary. n, i, x are all examples of the nth iteration, which could be interpreted as index, number of count but certainly not key or value.
Furthermore, whilst I agree abbreviations are not always better in this case they make the most sense. Consider the case (standard for loop):
let output = input[theNthIteration]
instead of
let ouput = input[n]
The latter, above, is much easier to read - rather than (for other programmers looking at this code) to try and decipher what theNthIteration is. Also, the more complex the for loops (nested), then that naming convention becomes even worse on all levels. When considering readability using n etc trumps anything else, every time. n only refers to an integer, i.e. the next step in the process and therefore doesn't require relatively complex naming conventions.
Finally, whilst certain types of programming aren't specifically math based, understanding more than just gcse maths (no offence meant to anyone) provides the programmer a more solid background which can be applied in multiple scenarios. For any programmer it should make sense to learn more math, at least common conventions and methodologies.
@amc tl;dr you can get by without understanding common math common conventions and methodologies but things could become difficult if you wanted to move away from just html and css or work with other developers.