# Fun with Numbers

Here is a simple and elegant way of establishing the relative sizes of the earth and the moon.
Start with a 3:4:5 triangle (shown in black outline in the diagram to the right), project a 3×3 square from the shorter side and then draw another 3:4:5 triangle off the other side of the square. From the bottom line of the resultant figure, project another square, this time 11×11. Draw a circle in each of these squares.

From the 3:4:5 triangle we can calculate the following figures:

3+4+5=12
3x4x5=60
12+60=72
12×60=720

You will recognise 12 and 60 as being the basis of how we measure time. The figure of 72 relates to an astronomical phenomenon called precession (because of the slow wobble of the earth’s axis, the night sky appears to revolve in a complete circle but not that you would notice. It takes 72 years to move through 1° of that circle) The next figure, 720 is the one which relates to our two circles in the above diagram. Multiplying this figure by the diameters we see –

720×3=2160
720×11=7920

The moon has a diameter of 2160 miles
The earth has a diameter of 7920miles.

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## 4 comments for “Fun with Numbers”

1. September 25, 2010 at 20:01

Piece of cake [once it’s explained].

2. Rob
September 25, 2010 at 23:50

And all that happened by chance?

3. September 26, 2010 at 07:25

I don’t buy that it is by chance.