"key concept" is not a mathematical term . A key concept is an important idea. Two key concepts in math are derivatives and integrals of functions. ( "function" is also a key concept.)
Everything is the most important thing in math. You are going to need math when you are older or to help you with your job now.
The most important concept of the enlightenment was to question things. Everything was to be examined, questioned, and examined.
Maybe the most important concept is probably bullying. :) -Michael B. ;)
they made stone heads
A math CONCEPT is a fancy way of describing the different ways and things you can and can't do in math. A math Concept can be 5!. That in term equals 5*4*3*2*1, which then = 120.