Posted by barbara on Saturday, June 6, 2009 at 11:52am.
Indicate whether the deductive reasoning used is an example of affirming the hypothesis or denying the conclusion.
If a number is divisible by 3, then the sum of the digits of that number is divisible by 3.
The sum of the digits of a number is not divisible by 3. Therefore the number is not divisible by 3.

teaching math  bobpursley, Saturday, June 6, 2009 at 12:03pm
The fallacy of affirming the hypothesis is based on the following hypothesis:conclusion set
If A then B, IF B then A.
The fallacy of denying the conclusion is
If A, then B; If NOT B, then NOT A
Does that help? 
teaching math  bobpursley, Saturday, June 6, 2009 at 12:04pm
If you are teaching Math, the way to teach these is to demonstrate with Venn Diagrams, in my opinion. STudents understand spacial arguments better than written logic.