Sololearn python bug? 🤨

Question

There is a wierd bug(?) that wasn't allowing me to finish simple task.
If i multiply simple number for example:
4000, 50, 49, 40, by 1.1
I expect to get results like:
4400.0, 55.0, 53.9, 44.0
However I get results like
4400.0, 55.000000000001, 53.900000000006, 44.0
It wouldn't be that confusing if it wouldn't be random

Try it yourself:
print(4000*1.1)
print(50*1.1)
print(49*1.1)
print(40*1.1)

Answer 1

Piotr Ś ,

what we can do depends a bit on what we are going to do with these results.

▪︎if it is just to output the number with a specific number of decimal places, we can use print() with f-string that can format the output. the numbers itself keeps as they are, but the output is according the arguments that are used with f-string

▪︎if we need these numbers for mathematical or comparison operations, we can use round() function which creates new numbers that are rounded to the specific number of decimal places.

▪︎for high precision calculations we can use the decimal module of python, that provides support for fast correctly-rounded decimal floating point arithmetic

an other way of doing the calculation can also help:

print(49*1.1, 49 * 110 /100) => results in: 53.900000000000006 53.9

.

Answer 2

Not only Sololearn code playground, It will give you the same output in any ide.
https://stackoverflow.com/questions/588004/is-floating-point-math-broken

Answer 3

Oh I see, thank you Simba, anyway how do you deal with it? In my example I had to compare two numbers by == or > etc, so this bug messed it all. Finally I just added round(x,2) to round particular part, but it feels insane to add it to all floats" just in case".

Answer 4

Shubham Bhatia good 😊👍but who asked 🤣🤣🤣😂😂

Answer 5

Oh thank you Lothar this is indeed a great reply:

*110/100, instead *1.1 seems to fix it :)

It's really great to have so friendly and knowledgeable community.

Answer 6

I like sololearn Coding 💪 playground. 💯