33*25.4

[DeaD_EyE]

Let me guess. You're converting inch to mm.

The slowest solution is to work with Decimals.

from decimal import Decimal



def inch2mm(inch, precision=None):
    value = float(Decimal(str(inch)) * Decimal("25.4"))
    # optional rounding if required
    if precision is not None:
        value = round(value, precision)
    return value

Another trick is to do the calculation with integers instead of floats.

print(33 * 25.4)
print(33 * 254 / 10)