Decimals

Decimals 

(Go to the bottom of the page for printable Decimal help notes.)

In our decimal unit we will be learning about the decimal place values tenths, hundredths, and thousandths.  We will also be comparing decimals and finding equivalent decimals.

 A decimal point is a dot that comes between the whole number places and the decimal places in a number.

 All the digits to the right of the decimal point are less than 1 whole.

 Decimals are special fractions with unwritten denominators of ten, a hundred, a thousand, etc.  For example: if the decimal is 0.1 the 1 is in the tenths place.  The fraction would be 1/10.

 Decimals are parts of a whole.  We can answer 3 questions to determine the decimal:

The Three Decimal Questions

1.      What is the whole and how big is it? 2.      Into how many equal parts has the whole been divided? 3.      How many of the equal parts are we using?

 Tenths are divided into 10 equal pieces.  If all ten pieces are used than we have 1 whole.

  Hundredths are divided into 100 equal pieces.  Each row on a hundredths square has 10 equal pieces.  If all hundred pieces are used than we have 1 whole.

 T housandths are divided into 1,000 equal pieces.  Each row on a thousandths square has 100 equal pieces.  If all thousand pieces are used than we have 1 whole.

  The standard form of a decimal is written in numbers.  For example: 0.1 

  The word name of a decimal is written in words.  For example: one tenth

  A decimal can be written in expanded notation.  Expanded notation means to add the each place value together.  For example:  0.1 + 0.2 + 0.3 = .123

  A decimal amount can be modeled on a place value mat.  For example: 

       This number line shows 1.9

 A zero at the right end of a decimal doesn't change the amount, but it does change the way the amount is named.  A decimal is named by the smallest decimal place.  For example:  0.1 is one tenth and 0.10 is ten hundredths.

  We can compare decimals and put them in order from least to greatest or greatest to least using the < (less than) or > (greater than) symbols. 

  Tenths > Hundredths > Thousandths.  Remember not to focus on ten, hundred, or thousand part of the word names.  Do not confuse their place value names with whole numbers.   A tenth is larger than a hundredth and a hundredth is more than a thousandth.  For example:  0.3 > 0.03 > 0.003 

  When you add and subtract decimals make sure to line up the decimals points and then add as usual.  For example:

 Equivalent decimals are decimals that are equal.  For example:   

 To review and practice decimals. 

  To practice adding decimals with number lines.

 To practice identifying decimals.  

 To practice putting decimals on number lines. 

  To practice making the largest decimal.  

 To practice comparing decimals.

 To practice identifying decimals. 

 To practice decimals to the thousandths place.

Decimal Names (docx file)

Decimals & Place Value Presentation (ppt file)

	PPT file: You need Microsoft PowerPoint to view this file. Download a free PowerPoint viewer for PC or Macintosh. Microsoft Office Compatibility Pack for PowerPoint 2007 File Formats
	docx file: You need the Microsoft Word program, a free Microsoft Word viewer, or a program that can import Word files in order to view this file. To learn more about the free Microsoft Word Viewer, visit the Microsoft Office Viewer for Word 2007 File Format.

Teacher Websites © 2009 SchoolWorld