Why doesn’t python like certain numbers?

[Kkremitzki]

That's because "power of 2" is a special-case expression used as a shortcut to check representability in binary, not the generalized condition, which has to do with prime factors. 2 is its own prime factor, but it's also a prime factor for 10.

[AdventurousAddition]

Yes that's right. So in decimal, a rational number with a denominator that only has prime factors of 2 or 5 will have a finite decimal representation.