floating point - Python Decimal Module - Undesired Float-Like Output?

Question

This I imagine is extremely simple - but why in the following are the two values for y not == 0? I thought the whole point of the decimal module was to get rid of the float dust ...The following is an extremely simplified version of a mathematical routine that passes numbers around as variables.

from decimal import * 
getcontext().prec = 2

q = Decimal(0.01)

x = Decimal(0.10) * Decimal(0.10)

y = Decimal(x) - Decimal(q)

print(x,y, Decimal(y))

'''
x== 0.010 
y== -2.1E-19 
Decimal(y) == -2.1E-19
'''

Answer 1

Try specifying the numbers as strings

>>> Decimal('0.10') * Decimal('0.10') - Decimal('0.0100')
>>> Decimal('0.000')