Go for it! I finished my ADN when I was 60 and just completed my BSN at 62. Now looking into Masters programs. If it's your dream don't let it go. As for the math, there's more calculations in school...
Have you looked at Hurst Review? It's online but I thought it was great. I passed NCLEX 2 1/2 years ago on my first try using Hurst. I've heard others have had very good success with this review too....
I agree with jak2010 that many ADN programs are harder to get into than BSN. At the initial information session at my school we were told you needed an "A" in A&P. I think if someone isn't able...