Account techniques (1959)

Do you know how to multiply or divide by 25 without using a calculator? And how to multiply in the mind multi -digit numbers? Can you quickly solve a long example? Can you find approximate roots from decimal fractions?
The book in front of you will help you learn this and much more. With its help, you will master the basic principles of a convenient oral and written account. Here all the necessary rules are listed for multiplying and dividing multi -digit numbers, simple and decimal fractions, as well as square roots and interest tasks. Having studied all the techniques, you will understand how to speed up the simplest calculations that you face daily: calculating the budget or making purchases in the store.
The book is written in an accessible language and does not require special knowledge. All examples are understood in detail, but for greater effectiveness it is recommended to solve them on their own