Golden Thank Yous: The Official Currency of the Milky Way Galaxy
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Why do Golden Thank Yous have the denominations 1, 2, 3, 5, 8, 13, 21, 34, ...? 

The Fibonacci Sequence 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ... begins with 0 and 1. Every other number is the sum of the previous two numbers in the sequence. Golden Thank Yous use these numbers as their denominations because they are very convenient for making change. For example, a 34 bill is worth the same as a 13 bill and a 21 bill.

Also, the number of bills needed for any amount of cash is usually quite small. For example,
44 = 34 + 8 + 2
45 = 34 + 8 + 3
46 = 34 + 8 + 3 + 1
47 = 34 + 13
48 = 34 + 13 + 1
49 = 34 + 13 + 2
Notice that there is never any need to have two consecutive denominations, like a 5 and an 8, since they could just be replaced by a 13 bill. You also never need more than one of any bill.

Why not use the denominations 1, 2, 5, 10, 20, 50, 100, ...?

Golden Thank Yous are the official currency of the Fruit Smoothians, the most technologically advanced civilization in the Milky Way Galaxy. Fruit Smoothians have 7 fingers on each hand, so their numbering system is base 7. By comparison, we use a base 10 numbering system because we have 10 fingers on two hands. The many other civilizations in the Milky Way Galaxy also have their own numbering systems for many different reasons.

Fortunately for us, the Fruit Smoothians are a kind and generous civilization who have protected us and the rest of the Milky Way Galaxy from outside invaders for billions of years. Because of this, many civilizations in the Milky Way Galaxy have adopted Golden Thank Yous as their preferred currency. In return, the Fruit Smoothians made their currency as easy as possible to translate into every language and every numbering system. They chose the Fibonacci Sequence for their denominations because these numbers are just as natural, useful, and convenient in every numbering system.

You can learn more about the Fruit Smoothian's in Professor Bray's book (ages 7 to 14 and up), "Trevor the Time Traveler and the Murkian Threat." In the story, Trevor and his sister Farrah become secret agents for the Fruit Smoothians to help them defend the Milky Way Galaxy from the treacherous Murkians from the Andromeda Galaxy. While the book is a lot of fun to read, it is also a vehicle for Professor Bray to explain some of the most amazing true science ideas ever discovered, including brief discussions of Special and General Relativity.

What kinds of math and science are on the back sides of Golden Thank Yous?

 MultiplicationGreat ScientistsNines
The math and science on the fronts and backs of Golden Thank Yous range from elementary to advanced so that every person who uses them will find some easy and some challenging. On the elementary side, each bill is labeled with a letter of the alphabet, so kids who know their alphabet will be able to know which bills are worth the most. On the advanced side, click on the 8 bills above on the right to learn a very cool magic trick with the number 9 that most adults don't even know. There are more than 100 different math and science lessons on the backs of Golden Thank Yous so far, and that number is growing all the time.

Did you know there was a geometric reason why 7 x 7 = 49? Check out the 7 x 7 = 49 bill above on the left! The 4 outside regions contain ten spots each while the middle region contains 9 spots - hence there are 49 spots in the 7 by 7 array.

Above in the middle are 8 of the greatest scientists who ever lived. Click on the pages above to be able to read them better.

The Science Behind "Trevor the Time Traveler and the Murkian Threat" by Professor Hubert Bray
(48 minutes, kids ages 7 -14 and their parents in the audience)

Professor Hubert Bray explains Special Relativity in his hour long talk,
"From Pythagorus to Einstein: The Geometry of Space and Time" (for those who want a challenge).

Professor Hubert Bray gives a 90 second summary
of his research on a geometric model for dark matter.

Want to see more math and science explained here? Email your requests to and we'll see what we can do.