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# M1 & M2 - When to round results and working? Watch

1. Hi,

I'm confused about when to round and to how many decimal places in M1 & M2.
Is it always to 2 significant figures when using g as 9.8? Or does it not matter?

2. (Original post by JLegion)
Hi,

I'm confused about when to round and to how many decimal places in M1 & M2.
Is it always to 2 significant figures when using g as 9.8? Or does it not matter?

Exam board?

For Edexcel you must always use 2 or 3sf in your final answer if you've used g in your working.

E.g. you could get an answer of 120g which you may think is fine to write as 1176. But you would lose a mark since it is not rounded to 2 or 3sf.
3. I know for aqa I think g is always 9.8 but they will accept answers used with 9.81 or watever not sure bput rounding other things as I hav the same problem I just write it all out and round to 3 s.f at the end which is kind of weird

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4. (Original post by notnek)
Exam board?

For Edexcel you must always use 2 or 3sf in your final answer if you've used g in your working.

E.g. you could get an answer of 120g which you may think is fine to write as 1176. But you would lose a mark since it is not rounded to 2 or 3sf.
Yes, edexcel.

So for long SUVAT questions, requiring several approximations, should I leave each result in terms of g?
Also, is it acceptable to leave my answers in terms of g (unless the Q says otherwise)?
5. (Original post by JLegion)
Yes, edexcel.

So for long SUVAT questions, requiring several approximations, should I leave each result in terms of g?
Also, is it acceptable to leave my answers in terms of g (unless the Q says otherwise)?
Do both. There is no harm in writing the answer in both forms as then whatever the mark scheme wants you will have satisfied it
6. (Original post by JLegion)
Yes, edexcel.

So for long SUVAT questions, requiring several approximations, should I leave each result in terms of g?
Also, is it acceptable to leave my answers in terms of g (unless the Q says otherwise)?
Yes it's good practice to leave all working steps in terms of g.

For the answer you can usually leave it in terms of g but I would always check the question. It's safer just to round all your answers to 2 or 3 sf.
7. (Original post by notnek)
Yes it's good practice to leave all working steps in terms of g.

For the answer you can usually leave it in terms of g but I would always check the question. It's safer just to round all your answers to 2 or 3 sf.
Great, thanks. You've probably saved me around 8 marks per paper.
8. 3 sig figs if in doubt

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