When you're stuck working on a tough Excel problem, it may help if you set that aside and work on something else for a while. The people at IBM research apparently do this, and have a monthly problem, Ponder This, that you can tackle when your brain needs a change of scenery. The problem is posted at the beginning of the month, and the solution is posted near the end of the month.
The first challenge was posted in May 1998, with this introduction:
"Here's what happened... Business Week recently ran an item about a "little book of big ideas" we published for the people here at IBM Research. "Sort of like the Tao for people who think about computers all day," they wrote. Seemed harmless enough. The story highlighted some of the simple things our researchers do to get a new perspective on things, ending with this one:
Ponder something else. For example: If a belt were placed around the Earth's equator, and then had six meters of length added to it, and you grabbed it at a point and lifted it until all the slack was gone, how high above Earth's surface would you be?