The Immense Power of Exponential Growth

My father taught me to play Chess.  And I am still a terrible player.  However, I do remember a wonderful little story about exponential growth he wove around the origins of the game.

Legend has it that an Indian King was presented with a beautifully hand-crafted chess board by a chess-master mathematician.  Delighted with the magnificent piece the king asked what the mathematician might like in return.  Humbly, the mathematician requested that a grain of rice be put on the 1st square, 2 on the second square, 4 on the third….. doubling at each successive square.   The King quickly agreed to his humble request.

Things were going really well (at first) and are summarised in the following table.

Square Number

Grains on that Square Total Rice on Board

1

1 1

2

2

3

3

4 7

4

8

15

5

16

31

6

32

63

7 64

127

8 128

255

After the first row, the total amounts to 255 grains of rice – barely half a cup full.  And some interesting relationships emerge.  The total rice on the board is given by

2(Square Number) -1. 

For example:

Square Number

2(Square Number) – 1

Total Rice on Board

1

21 – 1

1

4

24 – 1

15

8

28 – 1

255

Then, square 12  =

212 – 1

4095

Based on this how much rice might the King owe at the end of the second row of the Chess Board?

And at the end of the first half of the board? I.E. on the 32nd square?

16

216 – 1

65,535

32

232 – 1

4,294,967,295

So at the half way point (i.e. the 32nd square on the Chess Board), the King owes the mathematician over 4 Billion grains of rice.

Clearly the mathematician had a plan…

The Second Half of the Board – Exponential Growth

The numbers quite quickly become huge.  For example, at the 33rd square 233 – 1 = 8,589,934,591.  And at the 64th and final square……well I’ll let you have a go at that one. (But its over 7000 times the 2015 worldwide rice production!!!)  (See the same logic applied to M&M’s here).

Why is it important?  Well it illustrates the immense power of small things growing at constant rates.

Just like the mathematician, when a business has a plan, they may not expect to see “overnight success”.   Relying instead on the immense power of “constant growth” to see success delivered in due course – or as we might say, “On the second half of the board”.

Practical Considerations

Clearly things cannot grow at a constant rate forever.  Markets are subject to competitive forces, new entrants etc.  And in reality, markets and products behave a bit like a fire.  Starting slowly, then energetically consuming their fuel and finally diminishing to a smoulder.

Lessons from Chess

Dad also taught me that Chess was about “thinking ahead”.  (Apparently Bobby Fisher could visualize five moves ahead).

“What five small changes may have a massive exponential effect for you, 

On the Second Half of the Board’?”

 

P.S.  Have you calculated your “doubling time”

(See previous post (Doubling Time=100ln2/rate)).