[Python] Why no floating point error occurs in print(0.1* 100000) vs (Decimal(0.1)*100000) due...

I am studying numerical analysis and I have come across this dilemma.

Running the following script,

from decimal import Decimal
a = 0.1 ;
N = 100000 ;

# product calculation
P = N*a

# Print product result with appearent no error
print(' %.22f ' % P)
# Print product result with full Decimal approssimation of 0.1
print(Decimal(0.1) * 100000)


i realized that despite 0.1 not having an accurate floating-point representation, when I multiply it by 100000 (which has an exact floating-point representation), and increase the precision of how I print the result, I do not notice any error.

print(' %.22f ' % P) # Result: 10000.0000000000000000000000


This is in contrast to the case where I use the Decimal method, where I can see the error behind the product.

print(Decimal(0.1) * 100000)


Can anyone explain why this happens?

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