Teacher2Teacher

Q&A #5442

Teachers' Lounge Discussion: Percentage of change

T2T || FAQ || Ask T2T || Teachers' Lounge || Browse || Search || T2T Associates || About T2T

View entire discussion
[<< prev] [ next >>]

From: John

To: Teacher2Teacher Public Discussion
Date: 2002111210:07:20
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)"?

Post a reply to this message
Post a related public discussion message
Ask Teacher2Teacher a new question


[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || The Math Library || Quick Reference || Math Forum Search
_____________________________________

Teacher2Teacher - T2T ®
© 1994- The Math Forum at NCTM. All rights reserved.
http://mathforum.org/