Definitions
Numbers
Even Numbers

numbers divisible by 2

2,4,6,... 
Odd Numbers 
numbers not divisible by 2

1,3,5,7,... 
Whole Numbers
 0,1,2,3,4,..... 
 Integers include the whole numbers, but extend the range to include negative numbers.
 Prime Numbers are numbers with no factors other than 1 and the number itself.
 Rational Numbers are numbers that can be represented as a fraction. Integers
come under this classification because, for example
\[ 12 = \frac{12}{1} \]  The Reciprocal of a number is given by
\[ \mbox{reciprocal} = \frac{1}{\mbox{number}} \] For example :
The reciprocal of 3 is $\frac{1}{3}$
The reciprocal of 0.362 = $\frac{1}{0.362}$
Operations
 The Sum of two numbers is the result of adding them
 The Difference of two numbers is the result of subtracting the smaller number from the larger number
 The Product of two numbers is the result of multiplying them
 The Binary Operators are +, , x , and $\div$
 An operation is Commutative if the order does not matter. Addition and multiplication are commutative, subtraction and division are not.
 A Factor of a number is a number that divides that number exactly.
Fractions
 The top part of a fraction is called the Numerator
 The bottom part of a fraction is called the Denominator
Prime Numbers
A prime number is a number that can only be divided by 1 and itself.
For example : 3, 5, 7, 11, 13, 17, 19
 1 itself is not included as it does not have two factors.
Note
 The only even prime number is 2
 A product of prime numbers is, by definition, not itself a prime number
Shapes
Shapes with all sides equal are called regular. Otherwise they are called irregular.
Shapes with 3 sides are called triangles. Regular traingles are called equilateral.
Shapes with 4 sides are called rectangles. A regular rectangle is called a square.
Foursided figures with two pairs of parallel sides are called parallelograms