What are numbers? According to Wikipedia, "A number is a mathematical object used to count, label and measure. In mathematics, the definition of number has been extended over the years to include such numbers as zero, negative numbers, rational numbers, irrational numbers, and complex numbers."
Rational Numbers??? Irrational Numbers??? Complex Numbers??? WHAT???
Ok, let's break down the Math jargon.
A cardinal number tells "how many." Cardinal numbers are also known as "counting numbers," because they show quantity.
Here are some examples using cardinal numbers:
- 4 cats
- 10 friends
Ordinal numbers tell the order of things in a set—first, second, third, etc. Ordinal numbers do not show quantity. They only show rank or position.
Here are some examples using ordinal numbers:
- 2nd fastest
- 5th in line
A nominal number names something—a telephone number, a player on a team. Nominal numbers do not show quantity or rank. They are used only to identify something.
Here are some examples using nominal numbers:
- Bus 147
- Phone number 91234567
A rational number is a number that can be written as a ratio. That means it can be written as a fraction, in which both the numerator (the number on top) and the denominator (the number on the bottom) are whole numbers.
- The number 8 is a rational number because it can be written as the fraction 8/1.
- Likewise, 3/4 is a rational number because it can be written as a fraction.
All numbers that are not rational are considered irrational. An irrational number can be written as a decimal, but not as a fraction.
An irrational number has endless non-repeating digits to the right of the decimal point. Here are some irrational numbers:
π = 3.141592…
Although irrational numbers are not often used in daily life, they do exist on the number line. In fact, between 0 and 1 on the number line, there are an infinite number of irrational numbers!
And you think it ends here? Think again, there are also Prime Numbers, Cute Numbers, Perfect Numbers (yep that’s right CUTE and PERFECT), Complex numbers, Odd and Even Numbers, and the list goes on. So think twice if you think that teaching young children is an easy job!