Archive for January, 2010

Numbers: The basics

A number is a number, right?? Well, not exactly. There are different types of numbers. Kind of like a dog and a cat are both animals, but they are different types of animals.

Numbers and number systems are pretty basic in math, so let’s look at some definitions and think about why we need all the different types.

Let’s  Get Started

The numbers you use all the time are called the counting numbers.

Counting numbers – The most familiar and basic numbers. The numbers we counts with: 1,2,3,4,5,6…..

When we throw in 0, we have a whole new set.

Whole numbers – The counting numbers are zero: 0,1,2,3,4,5,6…….

Whole numbers were all that we needed for awhile – until we needed a way to talk about loss of money or yards in a football game or depths below sea level.

Integers – The whole numbers and their opposites.

An integer that is divisible by 2 is called an even number. If there is a remainder of 1 when the integer is divided by 2, the integer is called an odd number.

But what about when you share a cookie with your friends? You need a fraction to tell how much cookie you each get to eat. This brings us to the rational numbers.

Rational numbers – Numbers that can be written as a ratio of two integers. Fractions and decimals are ratios of integers. All the integers are rational numbers.

Irrational numbers – Numbers that cannot be written as the ratio of two integers.

Real Numbers – The rational numbers and the irrational numbers.

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