Keno Odds

In Keno 20 numbers are chosen from a total of 80. If, for arguments’ sake, you bet $1 and selected four numbers, this is how you work out the odds:

First, calculate how many groupings of four numbers are possible within the 80 numbers:

80 x 79 x 78 x 77
    4 x 3 x 2 x 1       = 1,581,580

Then you need to calculate how many ways four numbers can be chosen from the 20 selected numbers:

20 x 19 x 18 x 17
    4 x 3 x 2 x 1       = 4,845

In other words, out of the total four ticket possibilities available (1,581,580) the amount of tickets that chose all four correct numbers would be 4,845.

This means that your odds of picking four numbers correctly could be worked out as follows:

    4,845  
1,581,580 = 0.03 x 100 = 0.3% odds