This puzzle/joke has exploded this year. I have seen it on Twitter, Facebook and many blogs. Could it mean that engineering is really catching hold in Social Media circles? I hope so!
The answer: Because Oct 31 = Dec 25 or octal (base 8) 31 = decimal (base 10) 25
It is a mathematical equation for number systems in base 8 and base 10. We are most familiar with base 10 or decimal because we use it all the time. The penny, dime, dollar or 1, 10, 100 system. Octal is not used very often, but it is built on the same principle where 8 is the base. We use 8 digits (0-7) in octal, just like we use 10 digits (0-9) in decimal.
Here’s the conversion: 25 decimal is 8×3 (24) plus 1 or octal 31. It takes a little practice but once you get it – you’ll always have it – just like riding a bike.
Need help? Have a good math puzzle? Leave a comment or send me an email firstname.lastname@example.org