Dec 4, 2009

Posted by

Testing answers by casting out 9R...

This test is based uon a remarkable property of 9. When any number is divided...

Nov 26, 2009

Posted by

Approximating and rounding off

Before working out a problem, determine how accurate your answer must be. A...

Nov 22, 2009

Posted by

Results are what you want

In doing a problem, it’s better to think only of the results of each...

Nov 18, 2009

Posted by

Basic ways of simplifying calculatio...

Short-cut methods are based upon the principle of changing...