what does it mean when something has a 165% increase or like a 98% increase/decrease. I just can’t seem to understand it

Question

what does it mean when something has a 165% increase or like a 98% increase/decrease. I just can’t seem to understand it

In: 2

Answer 1

There’s a simple formula for % change (where positive is increase and negative is decrease):

percent change = 100 x (new value – starting value) / old value

So if you started with 83, and now you have 94, the % change is:

percent change = 100 x (94 – 83) / 83 = 13.25 (percent, and it’s an increase since it’s positive)

—–

If you want to go the other way, you can rearrange that formula to get:

new value = (1 + percent change / 100) * old value

So if you have 173 things, and you decrease by 35%, you have:

new value = (1 + (-35)/100) * 173 = (0.65) * 173 = 112.45.

where the -35 is because it’s a 35% *decrease*.

—–

Note that one common error is to assume that a decrease of 50%, followed by an increase of 50%, gets you back where you started. It doesn’t. Can you see why? Try calculating it.