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pythonpython-3.xpython-decimal

Dividing Decimals in python returns inaccurate results

>>> x = Decimal(1000)
>>> y = Decimal(.005)
>>> x * y
Decimal('5.000000000000000104083408559')

I expected the result to be just 5

>>> a = 1000
>>> b = .005
>>> a * b
5.0

Above is what I expected.

====

The original intention is to divide a DecimalField from Django. Should I convert the Decimal value to float instead? For me to expect accurate resuls?

Solution

  • Pass it as a string:

    >>> x = Decimal(1000)
>>> y = Decimal(".005")
>>> x * y
Decimal('5.000')

    The issue is converting some floats into decimal. Starting with a string wouldn't be an issue.

    As for your question: you should do the operations on a Decimal for it to be accurate.