Keno formula
for players

Apr 11, 2006 3:54 AM

The keno formula is used by keno employees and keno players to determine how many ways are on a keno ticket. It is best remembered by using the mnemonic device (memory aid), to wit:

   HAVE  

NEED

Here, the HAVE represents the number of groups that you have, and NEED represents the number of groups needed to construct a particular way. Take for example a ticket that has 15 spots grouped into five groups of three. It is clear that we HAVE five groups. If we want to play nine spot ways, it is also clear that we NEED three groups of three to make a nine. Therefore we start by substituting these values into the formula:

   HAVE  

=

   5  

NEED

3

The next step is to multiply the bottom part of the fraction down to one. This results in:

   5  

3 x 2 x 1

We then multiply the top part of the fraction down the same number of terms as the bottom part:

   5 x 4 x 3  

3 x 2 x 1

Simple multiplication produces the fraction:

   60  

=

10

6

Thus, there is a 10 way nine on this ticket. If we also want to play the 12s on this ticket, we need to proceed as follows: We HAVE five groups, and we will NEED four groups to make a 12. The initial formula will look like this:

   HAVE  

=

   5  

NEED

4

The next step is to multiply the bottom part of the fraction down to one. This results in:

   5  

4 x 3 x 2 x 1

We then multiply the top part of the fraction down the same number of terms as the bottom part:

   5 x 4 x 3 x 2  

4 x 3 x 2 x 1

Simple multiplication produces the fraction:

   120  

=

5

24

Thus there is a 5 way 12 on this ticket. If we have a 20 spot ticket grouped into 10 groups of two and we want to play eight spot ways, we proceed as follows: We HAVE 10 groups and we NEED four groups of two to make an eight. Setting up the formula as above yields:

   10 x 9 x 8 x 7  

=

   5040  

=

210

4 x 3 x 2 x 1

24

Thus there is a 210 way 8 on this ticket.

Well that’s it for this week! Good luck, I’ll see you in the lounge!