print(int(2.9999999999999998)) Python 3

Question

I noticed something as I tried printing a float as an integer. If you tried to print a float with 16 decimal places consisting of .9999999999999997 or any value below, the output will not round the number

Example: print(int(2.9999999999999997))
output: 2

But if we go up to .9999999999999998 it rounds the number

Example: print(int(2.9999999999999998))
output: 3

Does anyone know why this is the case? I am new to Python 3 and programming in general, so any help would be greatly appreciated.

Answer 1

Decimal is only the presentation. The computer stores number in binary.

Therefore, it stores 2.9999....8 as 3.000000

If you want to know the details, Anna explains very well in this Q&A :

https://www.sololearn.com/Discuss/1477626/?ref=app

Answer 2

https://docs.python.org/2/tutorial/floatingpoint.html