I must say .. this is the first time I’ve seen this method .. Hmmm – could be useful! Although, for client’s Income Tax Preparation .. I’ll probably just stick to my calculator!
SOURCE: 5 Min Life Videopedia
In case you are interested in this type of Math .. apparently it’s part of “VEDIC MATHEMATICS” as mentioned in the comments of the video.
n the Vedic system ‘difficult’ problems or huge sums can often be solved immediately by the Vedic method. These striking and beautiful methods are just a part of a complete system of mathematics which is far more systematic than the modern ‘system’. Vedic Mathematics manifests the coherent and unified structure of mathematics and the methods are complementary, direct and easy.
The simplicity of Vedic Mathematics means that calculations can be carried out mentally (though the methods can also be written down). There are many advantages in using a flexible, mental system. Pupils can invent their own methods, they are not limited to the one ‘correct’ method. This leads to more creative, interested and intelligent pupils