I failed FizzBuzz the first time someone gave it to me in an interview...
The specific failure was that I first attempted to solve by using repeated subtraction. The guy kept asking me to "solve it a different way", or saying "there is a better way to solve this". I tried using arithmetic tables, I tried using results about base10 remainders and I even tried using one of the corollaries to Fermat's little theorem to speed it up for larger inputs... every time I was told I was getting it wrong because "there was a better solution".
In the end he pointed out that the only solution he would accept was use of the mod operator.
Since then I have actively kept a tally: I naturally use the mod operator an average of twice a calendar year, it has always been in personal life code when dealing with complicated geometry problems, the bit of code containing it almost always fails on some edgecase because at the point of using mod it is convoluted.
Honestly sounds like a bad interviewer. repeated subtraction is a good first step and I would try to push more if that was the first implementation. But If you could derive a base 10 remainder you know conceptually what problem the mod operator is trying to solve.
a % b = a - (b * a/b) /assuming a sane language with integer division, else cast a/b to int/
Figuring the above operation (or getting close) is when you should more or less pass, and That's a good point to show the interviewee what the operation is. That should be the point of an interview problem, to show the thought process, not that you know fancy tricks.
But alas, I was shown an XOR swap in an interview last week and spent 3 minutes deriving it on paper instead of 3 seconds saying "oh yeah, a => b and b => a" to a trick that I haven't seen since college some decade ago. The current market loves tricksters, I suppose.
And yes, the actual real world use of modulo is surprisingly sparse, despite easily imagining situations where you could use it.
I am highly reluctant to use type casting as a mathematical function!! I was burnt by early languages struggling with this problem... Even modern languages still have issues with this! Try running this in Python3.11
FizzBuzz is a highly artificial problem. It makes sense that people who are not familiar with it will assume that there is an elegant solution. But in the end the right approach is to be very boring and to notice that you need to check for divisibility with 15 before you check for divisibility with 3 and 5.
FizzBuzz is a problem that doesn't have an elegant solution. That is the point: to see how you approach the problem. (there are 3 possible solutions, each in-elegant in their own way)
I don't like FizzBuzz because it over-weights the interviewees knowledge of the relatively obscure modulo operator. Yes, there are other ways to do it, but the expectation of FizzBuzz is that the candidate has that "Eureka" moment and remembers modulo.
If I need a "Non-Programmer Weed Out" question, I'd rather give a problem that is 1. as easy as FizzBuzz, but 2. is just 'if' statements and loops and cannot be solved by knowledge of a particular operator (or bit twiddling tricks).
The specific failure was that I first attempted to solve by using repeated subtraction. The guy kept asking me to "solve it a different way", or saying "there is a better way to solve this". I tried using arithmetic tables, I tried using results about base10 remainders and I even tried using one of the corollaries to Fermat's little theorem to speed it up for larger inputs... every time I was told I was getting it wrong because "there was a better solution". In the end he pointed out that the only solution he would accept was use of the mod operator.
Since then I have actively kept a tally: I naturally use the mod operator an average of twice a calendar year, it has always been in personal life code when dealing with complicated geometry problems, the bit of code containing it almost always fails on some edgecase because at the point of using mod it is convoluted.