Is it too much of a problem that in the STEP exams I did a question and stopped half way through did other questions and then came back to it at the end. Bit worried an examiner may overlook the fact that I'd continued further on . Thanks

Help! I think I've done a massively stupid stupid thing on step 1 today...
I answered all my questions and one of the ones i did was question 10 but I think I wrote on the front of the paper that I did question 9!!! Will it be marked as question 9 and I get no marks?!

Help I'm panicking!!

Thanks

$$
\frac{\mathrm{d^{2}y} }{\mathrm{d} x^{2}}+n^2x=0
$$
In the FP3 textbook (AQA) is says the auxiliary equation for this is
$$
k^2+n^2=0
$$
I'm just wondering how you get to this :)

One of the main things that worries me about STEP is that in a lot of questions I end up hitting a road block because I need to use a piece of maths I've never come across before. For example, I did a question yesterday and to make any progress into part 2 I needed to know that arctan(1/x)=pi/2 - arctan(x). This just seems so obscure and I had never seen it before, yet it stopped me in my tracks so I could only get 8/20 on a question. Obviously I know it now, but there seems to be something like this in a lot of questions I try.

Just a thought, would it be unhelpful to do the STEP III questions on the assignments if you're doing STEP I and II? Also, are the mechanics and stats questions the same level of hardness throughout all three papers or (for example) is the stats in STEP III harder than STEP I?