35% of 54 is calculated by:   0.35 * 54 = 18.9.

Check: What % is 18.9 / 54 ?   { 18.9/54 } *100= 0.35 * 100 =  35%

Note:

When using % the percent number, in this case 35%, you use that number divided by 100 to get the fraction needed to perform calculations.

Also The numbers we have, 35% and 54, each have only 2 significant digits so the answer is only good to 2 significant digits.  The 18.9 we calculated should strictly be rounded to 2 signivfcant digits, 19.  This is done when the numbers are measurement in say a scientific experiment.  Check with your instructor regarding his/her preferred treatment of significant digits.

Good Luck!   BruceS