Mental Math Shortcuts
Here’s a collection of time-saving math shortcuts, great for back-of-the-envelope estimates.
Time and Distance
60 mph = 1 mile per minute
- Going 60 mph and the exit is in 10 miles? That’s 10 minutes.
- Been driving a half hour? That’s about 30 miles at highway speeds.
Feet Per Second = MPH * 1.5
MPH = Feet Per Second * 2/3 (derivation)
- 60 mph …
Using JSON to Exchange Data
Programming Gotchas
Debugging with GDB
Crowd Favorites
Math & Numbers
- Mental math shortcuts, adding 1-100
- Understanding exponents and the natural log
- Div, Curl, Flux, Gradient and other Vector Calculus topics
Programming & Web Development
- Site speedups with HTTP caching, gzip compression
- Understanding Rails, Web debugging, and Javascrtipt
- Swap bytes with XOR, byte order, unicode
