I have a question. I had an experiment using a meter stick, pencil (round without flat sides), quarter(new state one) and penny (1981 or later one).  I had to balance the meter stick on the pencil to find the center of gravity. It was 45.5. I then placed the quarter on 32 cm. To balance the quarter, I had to place the penny on 81 cm.  So c.g.= 45.5cm  x= 81cm
Equation reads as follows:
L1=c.g.-32=___-32,  L1=___cms
calculate L2= m1/m2 (L1)=____ (    );  L2=____cms
experimental L2=  x-c.g. when stick is balanced
L2=_____-______;  L2= _____ cms
Percentage error= larger-smaller/calculated value  x 100
Percentage error= (      )-(        )/(        )  x 100
Percentage error=_________%

I put 13.5 on the first blank and -18.5 on the second. On the m1/m2 blank, I put 32/81 (-18.5) ; L2=      -7.31  On the experimental L2= 81-45.5=35.5.  Please let me know if I am doing this correctly. I don't know even where to begin with the percentage error.  Can you please help????????????