Objectives: By the end of this subtopic learners should be able to:
demonstrate familiarity with the concept of number type such as: odd, even, integer, natural prime and rational numbers.
use the number line to order numbers
Integers
An integer is a whole number that can be positive or negative, including zero.
Examples of integers are -34, -6, 0, 21 and 298.
These are numbers that can be written without a fraction component.
Natural numbers
These are positive whole numbers.
There are no negative numbers and no fractions.
It is a set of whole numbers which is used to find or count the number of objects.
Examples of natural numbers are 1, 2, 3, 4 …
Odd numbers
It is any whole number that cannot exactly be divided by two or are not divisible by two (2).
Odd numbers leave a remainder of 1 when divided by two.
Examples of odd numbers are 1, 3, 5, 7, 9…
Even numbers
Even numbers are the numbers which are multiples of two or numbers divisible by 2.
To identify an even number look at its last digit.
If the last digit is 0, 2, 4, 6 and 8 or even then the number is even.
Even numbers can be negative and positive.
Examples of even numbers are -234, -40, -2, 0, 86, 112, 584 …
Prime numbers
A prime number is a number that has only two factors, 1 and itself.
1 is not a prime number.
Examples of prime numbers are 2, 3, 5, 7, 11, 13.
Rational numbers
A rational number is a number that can be written as a simple fraction.
It is a number that can be made by dividing two integers.
It can be written as a fraction, in which both the numerator and the denominator are whole numbers.
Denominator is a natural number.
$\frac{1}{2}$ is a rational number.
It can be expressed as a ratio.
When expressed as a decimal, it will either terminate (end) or recur (endless but repeating a pattern).
Examples of rational numbers are $\{\frac{2}{5};\frac{1}{3};5...\}$
Square Numbers (Perfect Squares)
Whole numbers found by squaring (multiplying number by itself).
Examples of square numbers, 1,4,9,16,25….
Tally system
Tally system was useful when counting a large number of things (long back). In modern day they are most used in capturing fast going recordings. The tally system is grouped in five strokes, with the fifth one written across the other four.