A. Three different types of percent:
 
        Remember the term "parts per hundred" !!!!

 =>       # of parts / 100 parts

a. W/W% or weight/weight % is defines as the number of grams in 100 grams of a solid preparation.

b. W/V% or weight/volume % is defined as the number of grams in 100 milliliter of solution.

c. V/V% or volume/volume % is defined as the number of milliliter in every 100 milliliter of solution.

B. Methods for solving percentage problems:

a. Ratio and proportion:

 Formula:    If  # of PARTS/100  =   THEN  => amount of solute needed / Total V or W of product

V = volume
W= weight

b. 1% method:

 Formula: (1% of the total amount of preparation) X (number of percent) = ( the amount of active ingredient)