Float operations are not precise (0.1+0.2=0.30000000000000004), so don't use them for monetary calculations.

There are two workarounds to this:

1 (simple but not scalable) - convert the floats to integers, do the operations, then convert them back to floats

2 (complex but scalable) - create a class that handles the data (idea by Martin Fowler). There are a few libraries to do that, like Dinero.js

I think loanAmount and apr are the two variables that can be floats.