Count : To count means to find out the number of objects by adding one for every object.

Divisible : An integer $x$ is called divisible by an integer $y$ if the division $x:y$ has a remainder of zero. For example 4 is divisible by 2 but 5 is not divisible by 2.

Divisible by 2 : An integer $x$ is called divisible by 2 if $x$ is a multiple of 2. An integer is divisible by 2 if and only if it is even.

Even : Even can refer either to an even function or an even number.

Number : A number $x$ is a mathematical symbol representing a quantity.

Function : A function is a mapping in which every element in one set is mapped to exactly one element of a second set. Most often the mapping is described using a rule. For example the function $f(x)=x+1$ maps 2 to 3 and -1 to 0.

Graph : The graph of a function is the set of points $\{(x,f(x))\}$ that can be blotted in a coordinate system.

Local maximum : A local maximum of a function $f$ is an $x_0$ such that there exist $a,b$ with $a\lt x_0\lt b$ and $f(x_0)\geq f(x)$ for all $a\lt x\lt b.$ A local maximum can but does not have to be a global maximum.

Monotonically decreasing : A function $f$ is called monotonically decreasing if we have $f(x)\geq f(y)$ for every $x\lt y.$ For example the function $f(x)=-x$ is monotonically decreasing and so is the function $f(x)=e^{-x}.$ A differentiable function $f$ is monotonically decreasing if and only if $f^{\prime}\leq 0.$

Monotonically increasing : A function $f$ is called monotonically increasing if we have $f(x)\leq f(y)$ for every $x\lt y.$ For example the function $f(x)=x$ is monotonically increasing and so is the function $f(x)=x^3.$ A differentiable function $f$ is monotonically increasing if and only if $f^{\prime}\geq 0.$

Point : A point is an element in a space. Shapes are made of sets of points.

Squared : $x$ squared refers to the number $x^2=x\cdot x.$ For example 3 squared equals 9.