For rational numbers, Python has a Fraction class in the standard library that performs exact integer arithmetic: >>> from fractions import Fraction >>

For rational numbers, Python has a Fraction class in the standard library that performs exact integer arithmetic: >>> from fractions import Fraction >>> f = Fraction(0xFEDCBA987654321, 0x123456789ABCDEF) >>> f%1 Fraction(1, 5465701947765793) >>> f - f%1 Fraction(14, 1) That shows that 0xFEDCBA987654321 / 0x123456789ABCDEF = 14 + 1/5465701947765793 exactly. >>> math.log(5465701947765793, 2) 52.279328213174445 Shows that the denominator requires 52 bits which is slightly more than the number of mantissa bits in a 64-bit floating point number, so the result gets rounded to 14.0 due to limited precision.