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

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)

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

The different ways in which numbers slide up, down, sideways, diagonally.

Is the example in the post part of the fifth type of arithmetic?

1. Addition +
2. Subtraction -
3. Multiplication x
4. Division /
5. Modulo %

The first time I learned about modulo as its' own branch of arithmetic was long out of school already, I had only hazily heard of it, on a PBS Nova documentary in the 1990s about Fermat's famous theorem and when it was proven after centuries of failed tries.