Types of Number
Natural (Counting) Numbers
- Simply termed as the counting numbers, these start from 1 and go up to infinity (1, 2, 3, 4, 5, …). They exclude zero and negative numbers.
Whole Numbers
- This is a set that begins from 0, followed by all the positive integers (0, 1, 2, 3, 4, …). They are simply the natural numbers with the addition of zero.
Integers
- These include all positive and negative whole numbers, as well as zero (…, -3, -2, -1, 0, 1, 2, 3, …).
Rational Numbers
- These are any numbers that can be written as a fraction or ratio of two integers. Remember, this includes whole numbers and fractions, as well as decimals that terminate or recur.
Irrational Numbers
- These are numbers that cannot be written as a fraction or ratio of two integers. This includes decimals that never terminate or recur. Examples of these are √2 or π.
Real Numbers
- These are all the numbers on the number line including rational and irrational numbers. They also include all the integers, fractions and decimal numbers, except for imaginary numbers.
Prime Numbers
- These are numbers that have only two distinct positive divisors: 1 and the number itself. For example, the number 2 is the first prime number as it can only be divided evenly by 1 and 2.
Composite Numbers
- These are numbers that have more than two distinct positive divisors. For example, the number 4 is a composite number because it can be divided evenly by 1, 2 and 4.
Even Numbers
- These are any integer divisible by 2. If the last digit ends with 0, 2, 4, 6, or 8 it's an even number.
Odd Numbers
- These are any integer not divisible by 2. If the last digit ends with 1, 3, 5, 7, or 9, it's an odd number.
Remember, understanding these types of numbers is the first step in getting to grips with the fundamental concepts of mathematics.