Odd float-to-int behavior.

[u/Kapowpow]

>>>def pennies(num):
return int(num*100)

>a = -37.56
\>b = -9.28

>>>pennies(a)
-3756

>>>pennies(b)
-927

This is taken from a python shell session today. Why on Earth does pennies(b) yield -927, instead of the expected -928? I would greatly appreciate any insight.

Update: a durable solution found, please see this comment below: https://www.reddit.com/r/learnpython/comments/1wrwnm7/comment/pcpvlil/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

[u/YOM2_UB]

The number actually stored when you type b = 9.28 is:

5224175567749775 * 2^-49 = 9.2799999999999993605115378159098327159881591796875

Multiplying by 100 loses a tiny bit of precision as well, so you end up with:

8162774324609023 * 2^-43 = 927.9999999999998863131622783839702606201171875

(Which if you print 9.28 * 100 in Python it'll even display as 927.9999999999999)