The different ways in which numbers slide up, down, sideways, diagonally.
Is the example in the post part of the fifth type of arithmetic?
Addition +
Subtraction -
Multiplication x
Division /
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.
Yeah we just learned "by" was a standard term for multiplication. So increased by 80% was just 1.8 times whatever you started with. "Divide by" meaning multiply inversely
Language translating to artithmetic.
I'm sure it doesn't always line up, as we change language quite often.