Python Decimal

decimal.ipython

In [13]: from decimal import *

In [14]: getcontext().prec = 6

In [15]: ars_usd = Decimal(0.0641030)

In [16]: usd_ars = 1 / ars_usd

In [17]: usd_ars
Out[17]: Decimal('15.5999')

In [18]: price_usd = Decimal(100)

In [19]: price_ars = price_usd * usd_ars

In [20]: price_ars
Out[20]: Decimal('1559.99')

In [21]: # revert operation

In [22]: price_ars * ars_usd
Out[22]: Decimal('100.000')

In [23]: getcontext()
Out[23]: Context(prec=6, rounding=ROUND_HALF_EVEN, Emin=-999999999, Emax=999999999, capitals=1, flags=[Rounded, Inexact], traps=[InvalidOperation, DivisionByZero, Overflow])