How to avoid inaccuracies when counting different expressions in Python?

Question

Python

The essence of the problem is that there are many unpleasant and subtle points when counting different floating point numbers.
Well, for example, there is a rather trivial probability problem:

 The store has two payment terminals. Each of them can be faulty 
with a probability of 0.3, regardless of the other terminal. Find the probability that 
at least one payment terminal is working. 

The correct answer here is 0.91 , i.e. P = (0.3 * 0.7) + (0.7 * 0.3) + (0.7 * 0.7)
But the python interpreter gives a not very correct result ( 0.9099999999999999).
I know that this is due to the specific implementation of storing real numbers in memory.
But my question is, how exactly can one get around such problems when working with such numbers in Python?

Answer 1

Read about decimal and fractions