Mind-blowing, yet simple Multiplication Strategies

As a young engineering student I had to come up with ways to shorten my work during a time calculators were still mostly unheard of. This was the result. Looking at the relationships between numbers and their equivalents in order to multiply in simple manageable ways lends to the feeling of accomplishment and power over numbers. These techniques are not found in textbooks and are unique applications of known math facts. They are useful from day to day and often free one from depending on a calculator; and frankly with them, it is possible to decipher even more quickly. Not to mislead, these techniques do not work on all numbers, and yet there are hundreds of combinations for which they do. They are especially helpful for ACT's and SAT's on math sections in which calculators are not permitted and that are timed.