A *natural number* can refer either to a *positive integer* (which excludes negative numbers and zero) or a *counting number* (which excludes negative numbers but includes zero). The *set* of natural numbers is usually denoted by

A *negative integer* is any *integer* whose value is below zero. That is, -1, -2, -3, -4, -5, -6

A net is a plane figure that can be folded to form a polyhedron.

One possible net for a cube is shown

A polynomial in one variable is said to be non-monic, if the coefficient of the leading term is unequal to one. For example, \(2x^3+2x^2+3x-4\) is a non-monic polynomial, whereas \(x^3+2x^2+3x-4\) is a monic polynomial.

A *non-negative* integer is an *integer* that is not negative, and is either zero or positive. It differs from a *positive integer*, which excludes zero. Non-negative integers are 0, 1, 2, 3, 4, 5

*Non-zero whole numbers* are *whole numbers* that explicitly exclude zero. Non-zero whole numbers are 1, 2, 3, 4, 5, 6

A number line, like the one below, gives a pictorial representation of real numbers. An example is given below depicting the location of a negative decimal and a positive fraction.

A *number sentence* is typically an equation or inequality expressed using numbers and common symbols; for example, 10 + 10 = 3 + 7 + 5 + 5 could describe a situation where 2 packets of 10 coloured pens contained 3 red, 7 green, 5 yellow and 5 white.

A *numeral* is a figure or symbol used to represent a number; for example, -3, 0, 45, IX, π.

In the *fraction *$$\frac ab$$, * a* is the numerator. If an object is divided into

*equal parts, then the fraction $$\frac ab$$ represents a of these parts taken together; for example, if a line segment is divided into 5 equal parts, each of those parts is one fifth of the whole and 3 of these parts taken together corresponds to the fraction $$\frac35$$.*

**b***Numerical data* is data associated with a *numerical variable*.

Numerical variables are variables whose values are numbers, and for which arithmetic processes such as adding and subtracting, or calculating an average, make sense.