Figuring the house edge on progressive tickets

March 19, 2002 2:23 AM
by

share

So just how do you calculate the house percentage on a progressive Keno ticket? I know that you were left in suspense by last week’s column, mourning the “bad beat.”

Let’s start off by calculating the percentages on a typical straight $1.00 six spot:

$1.00 0.12982
$3.00 0.08561
$100.00 0.30956
$1,480.00 0.19090
House edge: 28.41 percent 

Let’s make the ticket a progressive, with initial pay outs as they stand and a 1-cent per ticket increase in the progressive 6/6 meter. Now you may reason that since the Keno game is going to pay you back, on the average, the 1-cent per ticket, that you are only really playing a 99 cent ticket with straight pay outs as above. Calculating the percentages we get ($0.99 ticket):

$1.00  0.12982
$3.00  0.08561
$100.00 0.30956
$1,480.00  0.19090
House edge: 27.69 percent 

Unfortunately, this is not the house percentage of this ticket, because it is in reality two bets: A $0.99 Ticket that pays out like above, and a 1-cent ticket with a house percentage of 0 percent. This is an error of omission that some writers of books on Keno simply don’t understand. Adding these two components together in proportion to the wager on each, we get:

0.99 x 27.69  = 27.41

Thus 27.41percent is the real house percentage on this ticket.

We can verify this by using another method. Since 1 cent will be added to the jackpot for every ticket played, we know that on the average the jackpot will have increased by $77.53. Thus the payouts should be, on the average,

 $1.00  

0.12982

$3.00  

0.08561

$100.00  

0.30956

$1,557.53  

0.20090

House edge: 27.41 percent

This coincides with the correct method above.

More simply, the house percentage of a progressive ticket is the house percentage of the base (initial) ticket less the incremental percentage (in this case 1 percent.) Thus 28.41 percent - 1 percent = 27.41 percent.

Of course all these calculations depend upon knowledge of the progressive increment percentage.

Next week: How to find out the incremental percentage.

If you have a Keno question that you would like answered, please write to me care of this paper, or contact me on the web via email at kenolil@math.net. Well, that’s it for now. Good luck! I’ll see you in line!