Lesson 1
Introduction to Whole Numbers

The whole number system begins with zero and counts upward through tens, hundreds, thousands, millions, and so on.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ...

The number line for the whole number system looks like this:


Whole number line

The scale for the whole number line begins with zero and runs to the right. How far does it run to the right? We can say that the whole number system extends from 0 to  (spoken as "from zero to infinity").

The whole-number system uses only ten characters--0 through 9. They are the characters of our familiar decimal numbering system. Note that the deci- in decimal means ten -- the total number of digits (fingers and thumbs) on our two hands.

0 1 2 3 4 5 6 7 8 9

Every number we might ever want to express can be written as a combination of these ten, simple digits.

The value, or magnitude, of a decimal number can also be indicated on a number line: You can see that the value of these decimal whole numbers increase from left to right. (Of course you can also say that the values decrease from right to left.)