Trick in Cracking Hard Boiled Eggs' Shells

I learned a new trick today, while volunteering in the kitchen. I used to crack the hard boiled egg shells by knocking it on a solid surface and peel them. The cook showed me that rolling the egg with your palm while applying light pressure which was quicker in cracking the egg and loosen the shell which should be easier to peel too.

Doing the trick on egg shells that are smooth with no crack after boiled and iced, I noticed that the majority of the egg whites also crack open with the shell. So, I first knock it once and then rolled it and then peel it.

Picture from: eateateatsleep