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# PHYA4 and PHYA5 Significant Figures Watch

1. Hey

I've been doing past papers for a while now in preparation for the upcoming exams, and I'm still unsure as to how many significant figures I give my answer to, I've always given it to the same number of significant figures as the question (which is mostly two) but I've also noticed some answers on the mark scheme are to three significant figures

1. Is there some kind of method or rule for significant figures?
2. Would I not be given the mark(s) if my answer was two significant figures but the answer was given in three (and vice versa)?

Thanks
2. Hi
Is this aqa? -er i kno what u mean it's quite confusing.. My teacher said to use the same no of sig fig as used in the question (which varies). Hope that's of some help!
-oh yeah also, make sure u use ur rounded answer in further calcs to make sure ur final answer matches their markscheme. Weird i kno but that's how it works... Good luck

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3. It only matters in the questions where it states, "Give your answer to an appropriate number of significant figures."
4. (Original post by Mortson)
It only matters in the questions where it states, "Give your answer to an appropriate number of significant figures."
I'm pretty sure it does matter even if it doesn't say this. To be safe use the full number throughout the calculations then give your answer to the same number of significant figures as the information in the question.
5. (Original post by internetstephen)
I'm pretty sure it does matter even if it doesn't say this. To be safe use the full number throughout the calculations then give your answer to the same number of significant figures as the information in the question.
This guy is right.
6. (Original post by internetstephen)
I'm pretty sure it does matter even if it doesn't say this. To be safe use the full number throughout the calculations then give your answer to the same number of significant figures as the information in the question.
Logical but sometimes that doesn't work. Cos if ur using sonething like G for example then that's 6.67x10^-11. But this is a rounded figure so ur final calculation is only ever going to be as accurate as this one. So say in part i of a question it generated an answer with loads of dp, that doesn't necessarily mean it's accurate (cos it's only as accurate as G) so u have to round straight away and use ur rounded answer in the next bit.
It's tricky i always make mistakes here. Good luck

This was posted from The Student Room's Android App on my GT-I9100
7. (Original post by Mortson)
It only matters in the questions where it states, "Give your answer to an appropriate number of significant figures."
Just found this on the mark scheme

4 The use of significant figures is tested once on each paper in a designated question or partquestion. The numerical answer on the designated question should be given to the same number of significant figures as there are in the data given in the question or to one more than
this number. All other numerical answers should not be considered in terms of significant figures.

You were right

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