50000 * 1.1 is followed by a decimal point.
50000 + (50000 * 0.1) calculated correctly.

I found

1. There are limitations when expressing numbers with a computer.
2. When converting a decimal number to a binary phenomenon that an infinite decimal number is generated.
3. When expressing an infinite number as a finite number, there are values that are exceeded or lost, resulting in a calculation error.

And there are workarounds such as toFixed(), Math object method, and library.
I understand a bit, but I have a question.

Question 1.
If I use methods such as toFixed(), Math object methods, libraries, etc., do I get 100% reliability without any errors?
For example, where calculations are important, such as in a bank, which method do you use?

Question 2.
50000 + (50000 * 0.1) gave no error.
However, unless a separate calculation error resolution method is used, When the number is changed, is there a there a calculation error?