Commutative Property of Multiplication
Pronunciation: /ˈkɒm yəˌteɪ tɪv ˈprɒp ər ti ʌv ˌmʌl tə plɪˈkeɪ ʃən/ ?
The commutative property of multiplication states that
multiplying two numbers will get the same result no matter which number comes first.
The order in which two numbers are multiplied does not change the product.
This is expressed by the equation: a·b = b·a.
Figure 1: Commutative property of multiplication cartoon
One way to remember the commutative property of multiplication is to use the root word,
'commute'. Commute means to travel from one place to another, such as commuting to work.
As diagrammed in figure 1, in the commutative property of multiplication, the variable 'a'
commutes to where the 'b' was, and the variable 'b' commutes to where the 'a' was.
Figure 2 - Representation of 2·3 = 3·2 using dots.
Figure 2 is a
of the commutative property of multiplication using dots. On the left is a rectangle
showing 2·3. On the right is a rectangle showing
3·2. Both have six dots in them. You can transform
the first into the second by turning the first on its side.
Figure 3: Manipulative showing the commutative property of multiplication.
Figure 3 is a representation of the commutative property of multiplication that uses
the length of a line segment to represent each number, and right angles to represent multiplication.
Notice that when we 'multiply' one by the other, it doesn't matter which comes first, the total area
is the same. Click on the yellow points of the two lines on top and drag the points. Dragging
these points changes the diagram showing that, for any values of 'a' and 'b', this property holds true.
- commutative. merriam-webster.com. Encyclopedia Britannica. (Accessed: 2010-01-04). http://www.merriam-webster.com/dictionary/commutative.
- Jones, Burton. Elementary Concepts of Mathematics, pp 31-34. MacMillan and Company, 1947. (Accessed: 2010-01-12). http://www.archive.org/stream/elementaryconcep029487mbp#page/n52/mode/1up/search/commutative.
- Bettinger, Alvin K. and Englund, John A.. Algebra and Trigonometry, pg 2. International Textbook Company, January 1963. (Accessed: 2010-01-12). http://www.archive.org/stream/algebraandtrigon033520mbp#page/n18/mode/1up.
- Fine, Henry B., Ph. D.. Number-System of Algebra Treated Theoretically and Historically, 2nd edition, pg 5. D. C. Heath & Co., Boston, U.S.A., 1907. (Accessed: 2009-12-19). http://www.archive.org/stream/thenumbersystemo17920gut/17920-pdf#page/n14/mode/1up/search/commutative.
- McAdams, David. Commutative. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem LLC. 2010-01-15. http://www.allmathwords.org/article.aspx?lang=en&id=Commutative.
Cite this article as:
Commutative Property of Multiplication. 2009-12-19. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/c/commutemult.html.
2009-12-19: Added "References" (McAdams, David.
2008-07-07: Changed manipulative from Geometer's Sketchpad to GeoGebra. Corrected spelling (McAdams, David.
2008-03-25: Revised More Information to match current standard (McAdams, David.
2007-07-12: Initial version (McAdams, David.