You are Here: Home >< Maths

# did I do this correctly? watch

2. The answer and how you worked it out is correct, but the way you have written your working out is wrong:

You cannot write 5 - 2 = 3 x 180 = 540 - it simply isn't true - you are saying that 5 - 2 = 540

You have 2 ways of writing it:
(5 - 2) x 180 = 3 x 180 = 540
OR
5 - 2 = 3
3 x 180 = 540

I am fairly sure that for this question it wouldn't matter, as I believe (not sure as I don't have the mark scheme) that the marks are all for the answer, but it is better to get into good habits
3. why is it only 2 marks if you're doing 3 steps ?
4. I would guess that it is a mark for calculating interior angle, then a mark for calculating exterior angle.
Since you can calculate the interior angle as (n-2)*180/n (n is number of sides) you could calculate interior angle in 1 step.

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 8, 2018
Today on TSR

### Edexcel C4 Maths Unofficial Markscheme

Find out how you've done here

### 1,111

students online now

Exam discussions

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams