Fallacies

 We have heard, read, and studied a lot many fallacies, mainly mathematical, (like how to prove 1 = 2). Though I have thought of recording some of them, there had been too many to do so easily. 

Nevertheless, it is better late than never. Here is one.

A humble question by a student.

My primary school teacher has taught us that multiplication distributes over addition like

8 * 7 = 8 * (4+3) = 8 * 4 + 8 *3  32 + 24 = 56. or

5 * 11 = 5 * ( 8 + 3) = 5 * 8 + 5 * 3 = 40 + 15 = 55.

But, it beats me why she missed mentioning that addition distributes over multiplication like

0.3 + (0.5 * 0.2) = (0.3 + 0.5) * (0.3 + 0.2) = 0.8 * 0.5= 0.4 or

0.5 + (0.2 * 0.3) = (0.5 + 0.2) * (0.5 + 0.3) = 0.7 * 0.8 = 0.56

Those who are intrigued by this can find out why and when this happens and many more such by getting hold of  the book

Mathematical fallacies, flaws and flim-flam Edward J. Barbeau