Python is automatically rounding large numbers with decimals

I need to perform the following calculation in Python:

(10^16) + (9 * 54945054708534.5)

The output it prints is:

5494505492376810.0

but this is incorrect as the solution should end in 0.5. I have tried setting my variables to floats but this does not help, I also make sure that I print the float to 1 s.f.

Below is the section of code where it is being calculated as well as printed (i is 8 in this case):

area = float(((10.0 ** i)**2.0)/float(2.0) + 9.0*area)
print(f'{i} {area:.1f}')

Since this is in a for-loop I need the area to be correct for subsequent iterations but it always messes up at i = 8 where the value of area goes from 10^15 to 10^16. I have tried on Python 3.6.10 and 3.8.8, both produce the same result.

Does Python auto round numbers after a while? How can I represent huge numbers in Python so that my calculations and prints are correct?

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