Most people I know will multiply 11s but doing the 10s method, which is pretty fast. You add some zeroes and add itself back in; nothing exciting. For...
This is a guide on how to easily multiply any number by 11 mentally and without the aid of a calculator. It can be a cool party trick or maybe you just need to multiply by 11 in a pinch. You never know, maybe after learning this trick the ladies(gents, whatever you're in to) will come flocking....or not.
Step 1: Limitations and Precautions
There is no real limit to what number you can multiply by 11 with this trick. Just be aware that as you move into larger numbers, they become a little more time intensive. The only background I would suggest to have in this trick is be really familiar with your basic addition tables and be quick. The quicker you are with simple addition, the quicker this trick goes.