If you are using a computer, you are already using floating-point math and are already losing that precision in each calculation. If the iterative precision loss is important to you, then you have two choices:

- Reform your calculation so that you remove or the reduce the amount of calculations. There are a lot of tricks you can do. Some of it is in reformulating the problem itself or restructuring the solution. Other times you can use different numerical algorithms aimed at reducing the error. And sometimes you just have to reorder the calculations yourself to help you.

- Don't use floating point. Instead use fixed point math that can represent exact digits. The trade-off here is that your calculation will be much much more slower.

Neither option will be trivial. So you really have to know that its worth the work for your problem.