But I use a method much faster than this
It's called 'Vedic Mathematics'
Vedic Mathematics has many techniques for other operations also... Like Long Division, Squaring, Square Roots... Solving Quadratic Equations etc... MENTALLY :D
It's all pretty awesome if one has the patience to learn it!
"Wherever you go, go with all your heart" - Confucius
1. How to Review and Analyze your Mistakes (Post by BB at GMAT Club)
2. 4 Steps to Get the Most out out of your CATs (Manhattan GMAT Blog)
My Experience With GMAT
1. From 650 to 710 to 750 - My Tryst With GMAT
2. Quest to do my Best - My GMAT Journey Log