How to: Back-of-the-envelope calculations
You might be asked to do some estimates by hand.  Refer to the [Appendix](#appendix) for the following resources:

* [Use back of the envelope calculations](http://highscalability.com/blog/2011/1/26/google-pro-tip-use-back-of-the-envelope-calculations-to-choo.html)
* [Powers of two table](#powers-of-two-table)
* [Latency numbers every programmer should know](#latency-numbers-every-programmer-should-know)