Decimals are . . . 2.3, .554, .01, 1.9999998, 2.1, etc.
Decimal number basic

Place value and the decimal number system
Any study of decimal numbers must begin with a good understanding of place value. In this module, you can study the concept of place value and have an introduction to the decimal number system. Also included on this page are the concepts of expanded form and word form of decimal numbers.

Comparing and ordering decimals
In this module, you can study how to compare two decimal numbers to see which is larger and how to put a list of decimal numbers in order from least to greatest.

Rounding to a decimal place
In this module, you can study how to round numbers to a whole number place or to a decimal place.

Significant figures
In this module, you can study what a significant figure is and how to round to a significant figure.

Standard Form and Engineering Notation
In this module, you can study two different ways to write very large and very small numbers in a format that makes them easier to use.
Calculating with decimal numbers
Representing and ordering numbers