Can subtracting reduce the number of Significant Figures a number has?
Posted: Mon Jan 25, 2021 4:42 pm
Say I have to subtract then divide:
0.7552g - 0.7241g = 0.0311 g <- Here we keep 4 decimal places because we are subtracting.
For my next step, I would like to divide by 768.95 g/mol
Will my rounded answer be 4.044*10^-5 mol or 4.04*10^-5 mol? The question boils down to can subtraction reduce the accuracy of a measurement. Since the subtraction answer came from two numbers with 4 sf accuracy, why would subtracting them (which only cares about the # of places after a decimal) decrease its accuracy to 3 sf? Should I just stick to the original sf accuracy in this situation since the calculations are separate steps, or rather reevaluate the sig figs the number has after my first step.
This question pertains to my lab for 14BL, but I have changed the numbers around so you aren't doing the work for me :)
Hoping someone can help!
Colm
0.7552g - 0.7241g = 0.0311 g <- Here we keep 4 decimal places because we are subtracting.
For my next step, I would like to divide by 768.95 g/mol
Will my rounded answer be 4.044*10^-5 mol or 4.04*10^-5 mol? The question boils down to can subtraction reduce the accuracy of a measurement. Since the subtraction answer came from two numbers with 4 sf accuracy, why would subtracting them (which only cares about the # of places after a decimal) decrease its accuracy to 3 sf? Should I just stick to the original sf accuracy in this situation since the calculations are separate steps, or rather reevaluate the sig figs the number has after my first step.
This question pertains to my lab for 14BL, but I have changed the numbers around so you aren't doing the work for me :)
Hoping someone can help!
Colm