A generation of programmers might disagree with you.
Multiplication instructions and hash tables (!) are easily worked around, as evidenced by decades of art and innovation programmed on that "terrible" CPU. There are still 6502 programmers today delivering games, art, demoscene, etc.
That CPU was a foundation of the home computer and console revolution: BBC, Commodore, Atari (consoles and computers), Apple, and Nintendo (NES).
I don't think that games, art and the demoscene can be used as evidence here. Implementing something like C# means you have a spec to implement. You have to be creative with the implementation without violating that spec.
All the three of games/art/demoscene on something like the C64 have a rough idea as the spec, but then you'll get creative about how much of that "spec" you can bend and violate to meet the technical limitations of the C64, while still being fun.
Math is crazy!... still don't want to study it though!
123456 = 1 * 100000 + 2 * 10000 + 3 * 1000 + 4 * 100 + 5 * 10 + 6 = 1 * (99999+1) + 2 * (9999+1) + 3 * (999+1) + 4 * (99+1) + 5 * (9+1) + 6
When checking whether it is a multiple of some k, you can add/subtract multiples of k without changing the result, and those 99...9 are multiples of both 3 and 9.
So 123456 is a multiple of 3 (or 9) iff
1 * 1 + 2 * 1 + 3 * 1 + 4 * 1 + 5 * 1 + 6 * 1 = 1 + 2 + 3 + 4 + 5 + 6
is. Apply the same rule as often as you want -- that is, until you only have one digit left, because then it won't get simpler anymore.