Binomial Expansion FAQ

Is the marking scheme really that particular when it comes to approximation questions?
- Yes and no. As I said, the important point is to understand that the expansion is infinite and the approximation is just an approximation, AND to show that you understand it ( by using $+\dots$ and/or $\approx$ at least once somewhere in the working). The exact way of writing (in regards to usage of $=$ or $\approx$ ) after that its up to your preference.

Why is it sometimes I get an approximation which doesn't agree with the calculator BUT is considered a correct answer (answer given by the book)?
- The question is technically wrong. ;)