Half Squares

 Pretty tricks for doing mental arithmetic are often useful. Here is one that is particularly nice.

 The Problems:

 You probably know that 5 x 6 = 30

Now calculate 5.5 x 5.5  ( or 5.52 ) on a calculator.

Can you see the connection?

 Try       2.52        (close to 2 x 3),                     7.52     and      19.52 

as well, to check your method.

 Can you see how the diagram below explains why the method works ?



Can you now see how to simply write down:         

 252     752      and      1952                as well?


Open the File as a Word Document


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Last modified: June 18, 2007