Percents

Things one must know:

• A part is some percent of a whole:
  PART / WHOLE = PERCENT / 100
  Set up a proportion like above to solve
• Change is the part, while the original is the whole
• 100% plus or minus a percent change equals the percent of the original quantity that the new quantity represents; ORIGINAL +/- CHANGE = NEW
• You can compute the percent change using the ratio of any two of the following: original, change and new.
• To solve successive percent problems choose real numbers, usually 100 is the easiest, and see what happens
• In a percent problem with unspecified amounts, pick 100 to represent the orginal value
• Simple interest: Principal x Rate x Time
• Set up a mixture chart with the substance labels in rows and 'Original', 'Change' and 'New' in the columns, this way you can keep careful track of the various components and their changes.