Wild About Math! Making Math fun and accessible

MMM #26 Been Around the World

Blinkdagger has MMM #26 posted. This one is tricky. We've received a number of different answers and even the incorrect ones are well explained!

So, if you want a Blinkdagger-style Math problem, give this one a try!

Here's the problem description:

Ever since Quan was a little boy, his lifelong dream has been to fly around the world in an airplane.

• Quan lives on an island wherein there are 100 airplanes, all created equally with identical characteristics.
• Each airplane has a fuel tank that contains enough fuel to fly exactly half way around the world.
• All of the airplanes travel at the same speed, and use their gas at the same rate.
• Airplanes can exchange fuel with other airplanes while in flight.
• The island is the only source of fuel.
• For the purposes of this problem, assume that there is no time lost refueling on either the air or ground.
• All airplanes must make it back to the island safely.

Question: What is the lowest number of airplanes required to allow one airplane to travel all the way around the world?

Check out the rules and submission information at Blinkdagger.