Significant Figures and Decimal Places in AS-level

[qpKillerqp]

Alsalamu Alaikum everyone! I want to know how they consider answers mainly for the 3 subjects

1. Physics
2. Chemistry
3. Math

Everytime I check the Mark Scheme,its either 2 or 3 s.f and I never new how to really know that.Please answer ASAP.
Thanks you and good luck

 

[yoyo00xx]

Same here for physics but math they give you the sgf on the first page

 

[Ahmad Sammy]

Math is to 3 significant figures unless it is:
1- stated otherwise (for example, write your answer to 3 decimal places, etc) <- Golden rule. Always follow his instruction if level of accuracy is mentioned in the question)
2- It's an angle. Angles should be written to 1 decimal place if in DEGREES unless stated otherwise. Angles in radians are treated as normal answers to 3 significant figures.
3- If your answer happens to be an exact answer. For example: 1.125 , 3.625, etc..They should be written without rounding off. For this, it is alright to write as a fraction if possible, not necessary. (which i prefer)

Something else teachers prefer is showing rounding off..If you get 3.2498. . . on your calculator, write down 3.249 and on the next line 3.25 and this should be your final answer.
Good luck to both of us

 

[Ahmad Sammy]

For physics, you generally write to 2/3 significant figures. You need to write your final answer to the level of accuracy of data that is given. For example if, he gives you values such as 5.0 ohm, 12V, etc and asks you to calculate something, your answer should be to level of accuracy as the data given (2 sf in this case)
However in the uncertainty questions, sometimes he gives the data to different significant figures. You should write to the LOWEST level of accuracy in the data.. For example
X +/- 0.01 - (1 sf)
Z +/- 0.050 (2 sf)
R +/- 0.010 (2 sf)
And asks you to find uncertainty, you choose to write to 1 sf.
Also the value, Y for example if he asks you to calculate you should use lowest level of accuracy of among X, Z and R.
Example:
X = 1.20 (3 sf)
Z = 0.75 (2 sf)
R = 3.25 (3 sf)
Then Y should be written to the lowest level, 2 sf.
That's it I guess.

 

[qpKillerqp]

Thank you very much man This really helps!