Boring Significant Figures question

[Faez]

Just finishing coursework and found out that some coursemates have rounded some initial answers to 2 d.p. rather than 3 s.f. which obviously affects the final results. What would be appropriate here for NADH conc. mg/ml? Thanks in advance

I'm thinking 2 d.p. as that's what we start with

If these are intermediate values you shouldn't round them (or at least, not excessively), that propagates errors. Just look at the first two values - 2 dp would be .02, .03, when actually the second concentration is twice the first.

Always round to the appropriate number of significant figures at the end.

Ah yes of course, that would be totally inappropriate. I've always had it in my mind that if you have a significant figure before the decimal round to 2 d.p. and if not then 3 sig figures, must've been taught that at some point. The original value was 0.01666666667 so in the following calculations should I use that or the rounded figure? Years since I've done maths... And thank you

Sorry didn't read properly. I have to round to show a value in the table but if I do that do I have to continue using the rounded number or should I use the original

Always plug the original back into your next calculation. The rounded figure is for display, only

Brilliant thank you both

Yes, what pickachew said.

Always think in terms of significant figures rather than decimal places when doing scientific calculations. If you've been doing multiplications/divisions, the final results shouldn't be quoted to any more sig figs than the least accurate of the input measurements.

Yep that all makes sense, thanks again