Åk 6–9
2.5 The Position System – The System of Tens
Today’s decimal position system was created in India during the 6th century and spread during the Middle Ages via the Arab world to Europe.  The position system we use is called the system of tens or the ten-base system.

You may have heard that we use a position system when we count and that we use the base 10.  What do you think this means?

Numbers are made up of 10 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.  We count with a base-ten system.

These digits then make up different numbers.  Each digit’s value depends on which place it has in the number.  This is called place value.

In each of the three numbers 432, 145 and 764, there is the number 4 included.  However, it does not lie in the same place in each of those three numbers.  It has very different values in those three numbers.  The digits placement or position in a number defines its value.

In the number 764, the four has the value of 4.
In the number 145, it has the value of 40.
In the number 432, it has the value 400.

You can show the position system in a table: