App idea that asks a series of mathematical and logical questions?

all. So I am a freshman CS student working on my first personal project. I want to create an app that would ask a series of questions. I have the general structure figured out. But I'm not sure how to create something that would return as incorrect or correct. I know I could use like an if/else type.

However I wanted to add something like "type this: 'Vladamir Nobakov was an exceptional writer'" and if they missed more than four characters, the return would say "incorrect". So how would I do that?

(I hope this makes sense, thank you in advance!! TL;DR is in bold)