The following example best illustrates the meaning of a "positional system":

Example 2.1.

What is the meaning of each digit in the number "2359"?

"9" means that there are 9 of "1"

"5" means that there are 5 of "101"

"3" means that there are 3 of "102"

"2" means that there are 2 of "103"

(Note: 102 = 10 × 10 and 103 = 10 × 10 × 10. The superscripts are called the indices. Click the following button to know more about indices.)

What are place values?

"1", "10", "102" and "103" are the so-called "place values" of "9", "5", "3" and "2" respectively.

Systematically, we can write 2359 as

2 × 103 + 3 × 102 + 5 × 101 + 9 × 100

Therefore, the number system we use nowadays is called the "base 10 number system" (or decimal number system) because the place values are powers of 10.