Mind Your Decisions

Monday Puzzle – What is the length of a spiral (helix) of a cylinder?

What is the length of a spiral (helix) that wraps around a cylinder of height 3 and a circumference of 4? . . . . M I N D . Y O U R . D E C I S I O N S . M O N D A Y . P U Z Z L E . . . .…

- 2 weeks, 6 days, 18 hours, 7 minutes ago

The Wind Chill Formula Explained (Video)

The wind chill is a measure of what it “feels like” when the weather is cold. The number is not made up–it’s a mathematical formula. This video explains the formula…

- 3 weeks, 2 days, 21 hours, 1 minute ago

Game Theory Tuesdays: The Race To 15 Puzzle

Today’s post is a puzzler from combinatorial game theory. I’ve read it in a few places, including Peter Winkler’s excellent book Mathematical Puzzles: A…

- 3 weeks, 5 days, 17 hours, 1 minute ago

Monday Puzzle: Can You Make A Rectangle With One Cut?

This math puzzler is a geometric one, somewhat inspired by leftover wrapping paper shapes. You have to cut the shape into two pieces, using all the area, that can form a rectangle. Can you…

- 3 weeks, 6 days, 18 hours, 8 minutes ago

New Video – Body Mass Index Formula (How To Calculate Your BMI)

One of the most popular New Year’s resolutions is to lose weight. On that note, I made a video explaining the mathematical formula for body mass index (BMI). People talk about the BMI…

- 1 month, 2 days, 18 hours, 8 minutes ago

The MindYourDecisions Expense Tracker and Budgeting Spreadsheet

Hope your 2014 went well. It’s time to start with the new year, and start a new spreadsheet to track expenses! When I started this blog, there were very few budgeting tools available,…

- 1 month, 4 days, 18 hours, 7 minutes ago

Game Theory In The News (Dec 2014)

This is the current installment of the monthly series “Game Theory in the News.” My hope is to highlight stories that can be used as case studies in the classroom, both so…

- 1 month, 5 days, 18 hours, 8 minutes ago

Monday Puzzle: What is x^x^x^… = 2?

I actually posted this puzzle in June 2013. This post is a video explanation. Can you solve the following equation? . . . . M I N D . Y O U R . D E C I S I O N S . M O N D A Y . P U Z Z L…

- 1 month, 6 days, 18 hours, 7 minutes ago

New Video – Calculate The Day Of The Week For Any Date Until 2099

January 1, 2015 is a Thursday. When will Christmas be in 2015? Or what about 2071? Because the calendar days in a year follow a regular pattern, there is a way you can calculate this in…

- 1 month, 1 week, 2 days, 2 hours, 46 minutes ago

New Video – Calculate The Day Of The Week For New Years Until 2099

January 1, 2015 is a Thursday. When will New Years Day be in 2017? Or what about 2071? Because the calendar days follow a regular pattern, you can calculate this easily in your head. This…

- 1 month, 1 week, 4 days, 1 hour, 45 minutes ago