Re: Random number access on the i5

On 04/02/2008, CRPence <crp@xxxxxxxxxxxxxxxxxxxx> wrote:

FWiW to get one winner of 10M requires only seventy balls, seven sets
of ten balls numbered zero to nine, spread across seven bins. The
problem is when there are for example 9499990 entrants. That is, if the
first bin selects ball-9, then the second bin must have ball-5 to ball-9
removed, to allow the game to continue. Similarly if the first six
numbers selected are 949999, then the seventh tube must have balls one
to nine removed, which means no seventh number need be selected; the
outcome is already known. Does that invalidate the game since it is no
longer seven distinct "Ten Choose One" [IIRC what they are called] problems?

Manual interference with the balls once a draw is under way is highly
undesirable for a lottery. Two alternatives are: 1) simply ignore a
ball that produces an invalid digit and draw a new ball for that tube;
2) continue with the draw and restart from scratch if the final number
is invalid.

ERNIE (Electronic Random Number Indicator Equipment) was a machine
that was used for many years to draw winning numbers for the UK
state-run Premium Bonds "savings" scheme. The numbers were as random
as they could be made and ERNIE would keep on drawing numbers until he
hit upon a valid winner.

<http://en.wikipedia.org/wiki/Premium_bonds>