Python sum function returning rounded result

Question

I am using python 3.8.5 to sum a list of floats as follows:

>> prices = [12.3, 11.99, 1.99, 5]
>> sum(prices)
31.279999999999998

here as you see, the sum function is returning a rounded result where the real sum is equal to 31.28. What sum has a same behaviour?

score 0 · Answer 1 · answered Oct 16 '20 at 10:15

This is caused by floats implementation, not sum. You might use decimal.Decimal to avoid that problem.

import decimal
prices = [decimal.Decimal("12.3"), decimal.Decimal("11.99"), decimal.Decimal("1.99"), decimal.Decimal("5")]
print(sum(prices))

Output:

31.28

1 Answers1