Place Value: the system in which the position of a digit in a number determines its value

Place value can be defined as the value represented by a digit in a number on the basis of its position in the number.

Decimal numbers are fractions or mixed numbers with denominators of powers of ten. In a decimal number, the digits to the left of the decimal point represent a whole number. The digits to the right of the decimal represent the parts. 

As move to left each place value is 10x larger, as move to the right each place value is 10x smaller.