I tried punching in 243 and it gave me an equation that resolves to 235.

https://www.wolframalpha.com/input?i=(lim+((x^2-100)%2F(x%2B10))%2C+x->13)^5+-+([lim((e^(8x)-1)%2Fx)%2C+x->0]+-+[[lim+((x^2-36)%2F(x-6))%2Cx->-5]+-+lim(cos^2+x+%2B+sin^2+x)%2C+x->36])

Tried it a few other times and it seems to sometimes like giving something that results in 3^5 (which would be 243 on its own) followed by subtracting a bit from it, which ends up making it the wrong answer. In the link above, it basically goes (3^5) - (8 - (1 - 1)), so if you only keep the first brackets it would be correct.

It seems feasible if you don’t imagine they’re all big novels. A lot of nonfiction you might borrow several of in one visit and not read front to back. Think recipe books, handicrafts, anything along those lines. Could also be smaller things like children’s books, poetry collections, etc., or some of the books were unusually expensive.