Description: This short book is a collection of simple and easily grasped tricks to speed up your mental arithmetic. It pays to master them as they will enable you to do calculations in your head without error, as with written calculations.
Brief description: Yakov Perelman (1882-1942) was a Russian and Soviet science writer and author of many popular science books. He has been known by his popular, witty and quite scientific works on physics, astronomy and mathematics, which are, moreover written in a marvelous language and are very readable.