What each fast-calculation method is, how it works and how it helps
Mental arithmetic is a set of methods that teach a child to calculate quickly in their head, without a calculator. Here the soroban (abacus), Vedic mathematics and Trachtenberg techniques are explained in simple language. Each method has its benefit, a worked example and an exercise — start learning for free.
The abacus, called soroban in Japanese, is a counting frame used for thousands of years and today it is the main tool of mental arithmetic. Each column stands for a place value (ones, tens, hundreds), and by sliding the beads you can represent any number.
The most important soroban rule! Know the friends of 10, and adding or subtracting any number becomes easy!
Adding numbers that go past 10! On the soroban, this means "carrying" — sliding a bead to the left!
The Big Brother method — adding through 5! Add 5, then subtract the extra. The secret of the 5-bead!
The "through 10" technique! First reach 10, then add the rest. A clever method!
A magical way to multiply any number by 11! Place digits side by side and add neighbors — done!
The secret method for multiplying by 9! Subtract 1 from the digit, then fill to 9. Fast and accurate!
The fast way to multiply by 12! Double the digit and add its neighbor. Simple!
An ancient Indian method for multiplying numbers near 100! A 3000-year-old technique that still works!
Multiply large numbers near 1000 using the Vedic method! 3-digit numbers — no problem!
Urdhva-Tiryagbhyam is the universal multiplication method of Vedic mathematics: any two numbers can be multiplied quickly in a single line using vertical and crosswise products.
Learn to square numbers quickly with special tricks — no paper or calculator, all in your head.
Division exercises! Learn to split numbers into equal parts!
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