How do you calculate percentage error?

In math. Here's the question:



a) Calculate (3x2.1)^3 / 7x1.2 --%26gt; equals 29.7675



b) Write the answer to part a) correct to 2 significant figures --%26gt; 30



c) Calculate the percentage error when the answer to part a) is written correct to 2 significant figures.



???How do you calculate percentage error?
Percentage error = ((30 - 29.7675)/29.7675)*100 = 0.78%.



Whenever you have to find a percentage variation, consider it as New value minus original value upon original value multiplied by a cent.How do you calculate percentage error?
((x2-x1)/x2)*100%

=((30-29.7675)/30)*100%

=0.00775x100%

=0.775 %

----%26gt;2 significant figures

= 0.78 %