I don't think that maths ability equates, odd though it sounds. I am thick as shit at maths, didn't pass GCSE, couldn't add if you took away my fingers, BUT...I am very financially astute.
I don't need to be able to work out compound interest precisely. I just need to know it exists and if I put X in, I can potentially get y out.
I understand what a higher interest rate means in terms of savings versus what it can mean in terms of mortgage payments (though I no longer have that worry, fortunately). All my lack of maths ability means is that if I want to know the actual numbers, I need a calculator.
On the whole, I'd say the most important financial understanding, above all other things, was drilled into me as a child. Income needs to be higher than expenditure.
I think we do tend to make budgeting and general financial comprehension into rocket science. It really isn't, and you don't need to be good at maths per se to understand it. In fact, some of my far more mentally capable friends understand less than I do.
I sometimes think that precisely because I am so poor at maths, I've had to simplify things. People who aren't so afflicted, like my husband who is much my superior intellectually in that regard, have a tendency to over-complicate that which is, in actual fact, quite a simple concept at its roots.