You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
<strong>Cosmic</strong> <strong>Game</strong> © Douglass A. White, 2012 v151207 206<br />
n: φ n ± φ -n Sum = Lucas Integer<br />
0 1 + 1 002<br />
1 1.618033989 - 0.618033989 001<br />
2 2.618033989 + 0.381966011 003<br />
3 4.2360679944 - 0.236067977 004<br />
4 6.854101966 + 0.145898034 007<br />
5 11.090169944 - 0.090169944 011<br />
6 17.94427191 + 0.05572809 018<br />
7 29.034441854 - 0.034441854 029<br />
8 46.978713764 + 0.021286236 047<br />
9 76.013155617 - 0.013155617 076<br />
10 122.991869381 + 0.008130619 123<br />
This is another way of generating the Lucas series that shows how it relates to the powers<br />
of φ using good old Egyptian reciprocal math. If you run the ratios on the reciprocals<br />
backwards, you also get φ. We already know how to calculate φ on a regular Senet<br />
Board of integer unit squares. If we have another Senet Board laid out in φ units relative<br />
to your integer unit board, we can work them together. For example, if we want to find<br />
φ 4 , we know that φ 2 is φ + 1, and we can calculate φ on our unit Senet Board and add 1<br />
unit to it to get φ 2 . <strong>The</strong>n we multiply this by 3 by simply marking off 3 string intervals<br />
of φ 2 . Next we subtract a 1-unit interval, and lo and behold, we have an interval that is<br />
φ 4 in length. An Egyptian could do this on his Senet Board with a piece of string as fast<br />
as you can by pecking on your electronic calculator.<br />
Now we will use φ to calculate an Egyptian approximation to 4 √10. <strong>The</strong> value of φ is<br />
about 1.618. Recall that the altitude of the Benben pyramidion on our φ pyramid is √φ,<br />
which is about 1.272. We need to make a line segment that is √30 units long. We can<br />
do this, because we know how to get √10 = 3.162 and √3 = 1.732 on our Senet Board.<br />
<strong>The</strong> product of these will be √30 = 5.477. <strong>The</strong> Egyptian scribe can find this several<br />
ways. He can measure his two lengths and then calculate the product arithmetically, or<br />
he can mechanically use % as his standard unit and measure off 1.732 units with his Oper<br />
unit standard string or measuring rod that he has calibrated like a meter (cubit) stick.<br />
Once he has √φ and √30, he draws a right triangle with these dimensions for its two legs.<br />
<strong>The</strong> hypotenuse is √(30 + φ) = √31.618, which is very close to the square root of<br />
10×3.162. He measures that to be about 5.623 and then divides that by % = 3.162. He<br />
gets 5.623/3.162 = 1.7783, which is a pretty accurate approximation of 4 √10, as you will<br />
see if you enter 10 on your calculator and punch the √ key twice. Our ancient scribe has<br />
found the answer using nothing more than the Benben stone on the Great Pyramid, his<br />
Senet Board, a piece of string, and some pen scratch calculations. Later we will show<br />
you yet another very simple averaging method that an Egyptian scribe could use for<br />
quickly finding square roots of any number, whole number or otherwise. For an ancient<br />
scribe, using geometry might have been faster than calculating numerically on papyrus.