Fractions are quite complicated as presented. Adults usually don't see it that way as they are familiar with the implicit framework around fractional operations.
But I *can* figure out a pretty good estimate for the square root of 95 by hand-- actually with Newton's method I can figure out a very good estimate--
If she doesn't, she isn't remotely ready for calculus.
Part of the problem, as I see it, is that math classes don't go back and review concepts from earlier years. Those of you who remember are lucky. If I thought my daughter would learn all the basics she's forgotten, or how to do problems without a calculator, I'd be more than thrilled to have her take a remedial class. I just don't see it happening. The name of the "remedial" class is Elementary Algebra 2.