Mental Addition and Subtraction

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Intermediate Multiplication
Episode 7 of Secrets of Mental Math
Take mental multiplication to an even higher level. Professor Benjamin shows you five methods for accurately multiplying any two-digit numbers. Among these: the squaring method (when both numbers are equal), the close together method (when both numbers are near each other), and the subtraction method (when one number ends in…
Advanced Multiplication
Episode 11 of Secrets of Mental Math
Professor Benjamin shows you how to do enormous multiplication problems in your head, such as squaring three-digit and four-digit numbers; cubing two-digit numbers, and multiplying two-digit and three-digit numbers. While you may not frequently encounter these large problems, knowing how to mentally solve them cements your knowledge of basic mental…
Divide and Conquer
Episode 4 of Secrets of Mental Math
Turn now to the last fundamental operation of arithmetic: division. Explore a variety of shortcuts for dividing by one- and two-digit numbers; learn how to convert fractions such as 1/7 and 3/16 into decimals; and discover methods for determining when a large number is divisible by numbers such as 3,…
Go Forth and Multiply
Episode 3 of Secrets of Mental Math
Delve into the secrets of easy mental multiplication: Professor Benjamin's favorite mathematical operation. Once you've mastered how to quickly multiply any two-digit or three-digit number by a one-digit number, you've mastered the most fundamental operations of mental multiplication and added a vital tool to your mental math tool kit.
The Art of Guesstimation
Episode 5 of Secrets of Mental Math
In most real-world situations: such as figuring out sales tax or how much to tip: you don't need an exact answer but just a reasonable approximation. Here, develop skills for effectively estimating addition, subtraction, multiplication, division, and square roots.
How to Boost Your Physical and Mental Energy Series
Wouldn't it be great if you could wake up every morning full of life and enthusiasm for a new day? Most of us no doubt feel energetic some of the time, but the stressors and responsibilities of life inevitably take their toll, leaving us feeling worn out. But what if…
The Joy of Pi
Episode 12 of The Joy of Mathematics
Pi is the ratio of the circumference of a circle to its diameter. It starts 3.14 and continues in an infinite nonrepeating sequence. Professor Benjamin shows how to learn the first hundred digits of this celebrated number, making it look as easy as pie.
Math in Your Head!
Episode 1 of Secrets of Mental Math
Dive right into the joys of mental math. First, learn the fundamental strategies of mental arithmetic (including the value of adding from left to right, unlike what you do on paper). Then, discover how a variety of shortcuts hold the keys to rapidly solving basic multiplication problems and finding squares.
Memorizing Numbers
Episode 9 of Secrets of Mental Math
Think that memorizing long numbers sounds impossible? Think again. Investigate a fun: and effective: way to memorize numbers using a phonetic code in which every digit is given a consonant sound. Then practice your knowledge by trying to memorize the first 24 digits of pi, all of your credit card…
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Gain new insight into the relationship between food and energy. The good news here is that counting calories and obsessing over dietary numbers might actually be counter-productive to good health. Instead, learn how to be mindful and follow a few sensible guidelines. The lecture ends with a powerful lesson on…
The Speed of Vedic Division
Episode 8 of Secrets of Mental Math
Vedic mathematics, which has been around for centuries, is extremely helpful for solving division problems: much more efficiently than the methods you learned in school. Learn how Vedic division works for dividing numbers of any length by any two-digit numbers.
The Joy of Mathematical Magic
Episode 24 of The Joy of Mathematics
Closing the course with a magician's flair, Professor Benjamin shows a trick for producing anyone's phone number, how to create a magic square based on your birthday, how to play "mathematical survivor," a technique for computing cube roots in your head, and a card trick to ponder.