To: Teacher2Teacher Public Discussion
Subject: Increase vs. decrease
I like the simplicity of "(new - old)/old" and in fact have used that myself to remember the principle. My question is in regard to the percentage of change when the old number is a negative value. Let's say you are comparing annual net earnings. In 2000, your company was in the red $50 (just to keep it simple), but in 2001 your company was in the black $200. That's a $250 increase which logic would say was a 500% increase. However the simple formula above returns a 500% decrease: (200 - (-50))/-50 = -5 Should the formula actually be "(new - old)/absolute value(old)"?
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