In archiving some old files on CPM disks from way back, I came across this
note I wrote to a friend. It describes a way to calculate the population
Tribbles using an HP calculator (I think I was using an HP-67 back then)
enjoy.

-J
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Another interesting side note: I have discovered the
"Tribble Population Function". Last night, I was watching my tape
of "The Trouble with Tribbles" and I heard Spock spout off
another one of his numbers (this time the population of tribbles
in the grain compartment), so I decided to put him to the test.
He said tribbles have an average litter of 10 and reproduce every
12 hours. He also said he assumed one tribble managed to find
it's way into the quadrotriticale 3 days ago and this would
result in a total population in the cargo hold of: 1,771,561. To
make a long story short, I should have known better than to doubt
Spock's figures, he was right! Look at the program:

LBL A
STO 0
1
0
x
RCL 0
+
RTN

Key in the initial population (1 tribble) and keep hitting
"A". You will see the population grow at 12 hour intervals. On
the third day you will see: 1771561.
Also, the first generation from one tribble is 11 (10 babies
and the one parent). Notice in the scene where Kirk goes to
sickbay with a headache: Kirk says McCoy has 11 tribbles in the
container. This happens shortly after Uhura gave McCoy one
tribble in a rec room scene earlier!

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It's nice to know Gene & crew actually ran the numbers to ensure the
dialogue would be correct.