Why lying with maths is so easy, the average person, even in developed countries is practically innumerate (massive hyperbole, but the fact lying with numbers is easy, still stands)

In the same vein, if the volume on your phone is on 1, and you increase it to 2, it has increased by 100%

Did this turn into an /iamverysmart thread ?

Even more confusing when you hear that the odds of catching a disease have increased by a %. In many ways odds can be more intuitive, but we're so used to working with simple probability that it's a total nightmare to wrap your head around at first.

Convert percentage to fraction, i.e, 80% become 0.8 Then multiply with initial value

If it says 80% more use initial + (initial*80) or simply initial*1.8

Or if it says 80% less, use - in above calculation or multiply by 0.2

I find percentages more neat when used as fractional number Edited to escape the multiplication symbol

hopeful-weirdo just needs to be told to consider what increasing by 500% means and it'll click.