The zero and the counting numbers (1,2,3,...) make up the set of whole numbers. But not every number is a whole number. Our decimal system lets us write numbers of all types and sizes, using a symbol called the decimal point. As you move right from the decimal point, each place value is divided by 10.
For example .3 means 3/10
.03 means 3/100
.003 means 3/1000 and so on
,753 means 753/1000
Here the 7 is in the tenths position, 5 is in the hundreths position and 3 is in the thousnaths position