Advanced Mental Multiplication: (Algebra of Arithmetic) Book 20 of In A Minute Series

In this book we’re going to examine some ultra-fast ways to multiply numbers. In the original book, Multiplication - In A Minute, we saw a technique to apply for every situation for the times tables, and then for numbers that are 2 digits in size, as well as 3, and 4 digits.

We then saw in further books this method being applied for decimals, percentages, standard form and quadratics. Later in the book, I will explain the algebra behind how this works. This is what I call ‘Algebraic Arithmetic’. However I don’t call it this at the start as it’s somewhat of a scary name. However, that is why the book has this subtitle.

Once we’ve looked at examples such as
7 x 9
and
19 x 23
we’ll look at squaring larger numbers manually.

We’ll also then look at ‘doing the reverse’ of this, square rooting these back again. Once we understand how this works, we’re away.
After that, we’ll look at a way of becoming more familiar with square numbers, by using them to find other square numbers.

We’ll examine how we can check our answers are correct, in seconds, and without having to divide.
We’ll then use this technique to perform a couple of magic tricks - useful for parties! This will have your friends scratching their heads and thinking you are some kind of wizard.
To finish, we’ll look at the algebra behind these systems, and see how they work. We will find them very simple, and you’ll likely be amazed they are not more widely known.