Thanks! I get it now

There is no decimal part, so no .0. You choose the greater prefix you actually exceed:

• 100,000 ohms don't exceed 1Mohms => 100k ohms
• 100,000,000 ohms exceed 1kohms and 1Mohms, choose the greater => 100M ohms

Could anyone help me with the prefix part? How does it choose k vs M? Also, in cases of 5.0, how is the '.0' eliminated?

Fastest - avg 0.5μs

Random test cases are generating negative numbers in Golang version (as said below), but even more: test fails both if you convert negative numbers to positive (-number) and if you work with them as negative values...

8 -> 1000 -> true

15 -> 1111 -> false
???

Could you add a link to some page where the roman numerals are fully explained?
I had a couple of doubts... so many years since I was taught this at school... x_x

Beauteous

Oh right - I missed that part. Thanks for pointing it out.

Seems you didn't try it by yourself.
Take a look at line 5

colors = (bands + ' ').split(' ')

It sets a default value for color[3] -thus default value for tolerance- even if none is passed.

This line will fail: tolerance = code[colors[3]]
if there is no tolerance provided ('index out of range')

are you using print instead of return?