[Note: the formula I use and how I use it is results from trial and error only. I don't claim it to be mathematically 'correct'. It just works.]
This is for states with a pick 3 AND pick 4 game that comes right after the pick 3 draw.
You can use the midday draw to pick the evening number, but I think it works best to keep the draws separate. The results will frequently be similar so you can also play commonalities. After doing it for a few days you'll get a feel of how best to play it. Suggested bet is straight/box.
Here goes...
Use the last seven balls drawn - pick 3 and pick 4.
Example: IL 8/28 Sat. Eve. results: 9-7-2 / 1-0-2-0
Write the digits out in sequence like this:
9,7,2,1,0,2,0
Go to this web page: http://www.easycalculation.com/statistics/standard-deviation.php
Enter your seven digits into the field as shown above and calculate. It will determine several results but what we are interested in is the last field, 'Variance (Population Standard Deviation)'.
Having done this, the result is 10.85. We will round off to 11. Use regular rounding-off rules.
Add this number (11) to the very last ball drawn, which in this case is '0', the last digit of the pick 4 game.
My worksheet looks like this:
9,7,2,1,0,2,0 (0 + 11 = 1)* (*use lottery math)
In this example, digit '1' will be the first number of the next draw.
For the next digit we will revise our seven number digit set by eliminating the oldest ball drawn (first ball of the last pick 3 draw) which is '9' in the example, and adding the new number ('1') at the end of the series.
The new seven-digit series is
7,2,1,0,2,0,1
Calculate a new variance with your new seven-digit number set. The result is 4.97 which we round off to 5. We will add 5 to the first digit we created ('1').
Now my worksheet looks like this:
9,7,2,1,0,2,0 (0 + 11 = 1)
7,2,1,0,2,0,1 (1 + 5 = 6)
6 will be our second digit.
Repeat last step for third digit like so:
9,7,2,1,0,2,0 (0 + 11 = 1)
7,2,1,0,2,0,1 (1 + 5 = 6)
2,1,0,2,0,1,6 (6 + 4 = 0)
0 will be our 3rd digit.
That's all there is to it. Our KEY number is 1-6-0. For best results, use key number and one digit-up/one digit-down variations on the key number to fit your budget. Here are ten variations as an example:
160 - 260 - 060 - 170 - 150 - 161 - 169 - 171 - 159 - 271
(note: for the pick 4 game just continue the process four more times. Not as reliable for pick 4.)
Good luck!