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Rader's NUMBERNUT.COM. Advanced Math. Maths Solutions - home page. Maths Quizzes - home page. Online Maths School. Motivating children to succeed. Trachtenberg system. The Trachtenberg system is a system of rapid mental calculation. The system consists of a number of readily memorized operations that allow one to perform arithmetic computations very quickly. It was developed by the Russian Jewish engineer Jakow Trachtenberg in order to keep his mind occupied while being held in a Nazi concentration camp. The rest of this article presents some methods devised by Trachtenberg. The most important algorithms are the ones for general multiplication, division and addition[citation needed]. Also, the Trachtenberg system includes some specialized methods for multiplying small numbers between 5 and 13. The chapter on addition demonstrates an effective method of checking calculations that can also be applied to multiplication.

General multiplication[edit] The method for general multiplication is a method to achieve multiplications with low space complexity, i.e. as few temporary results as possible to be kept in memory. Times the next-to-last digit of . Example: Web. HomeEdResources : Links. A to Z of Maths Is Fun. BetterExplained. The average is a simple term with several meanings. The type of average to use depends on whether you’re adding, multiplying, grouping or dividing work among the items in your set.

Quick quiz: You drove to work at 30 mph, and drove back at 60 mph. What was your average speed? Hint: It’s not 45 mph, and it doesn’t matter how far your commute is. But what does it mean? Let’s step back a bit: what is the “average” all about? To most of us, it’s “the number in the middle” or a number that is “balanced”. The average is the value that can replace every existing item, and have the same result. One goal of the average is to understand a data set by getting a “representative” sample.

The Arithmetic Mean The arithmetic mean is the most common type of average: Let’s say you weigh 150 lbs, and are in an elevator with a 100lb kid and 350lb walrus. The real question is “If you replaced this merry group with 3 identical people and want the same load in the elevator, what should each clone weigh?” Pros: Cons: