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 = $\frac{1}{0.362}$

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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.

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Fractions


  • The top part of a fraction is called the Numerator
  • The bottom part of a fraction is called the Denominator

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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

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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.

Four-sided figures with two pairs of parallel sides are called parallelograms

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