RUNDOWNS
When we go back 20 some years, rundowns were quite common particularly in Pick 3 as a workout to come up with numbers to play. At that time commonly you found the +111 +123, maybe even -111 and -123. No others. Typically the workout was done with pencil and paper. Numbers played were the numbers based on the rundown, not the modern concept to mix and match of the digits on the rundown chart.
The problem with the pencil and paper approach is obviously, it is error prone. We easily make mistakes, not on purpose, we get distracted, we are all humans. So right when I started to offer offline programs and add basic workouts to my web site (mostly free), I included - besides the other common workout (Tic-Tac-Toe) - also Rundowns, of course. But I did not stop with the 111 and 123 Rundowns, I added quite a few additional ones
One of first different one was 317. It became quickly a very much liked rundown for various reasons. And it is still today one of the "classic" rundowns if you wish.
Why 317? Before I answer the question, a little more info about rundowns in general is needed.
First you have to realize some of the flaws of the basic rundowns and also the limitation of certain digits. As the rundown typically uses so-called Lotto Math, add and subtract without carry-over, back then I pointed out the flaws early on.
Rundown 111 has an issue with types; triples, doubles and singles.
When you use the previous draw as a start number and that number happens to be a triple, e.g. 333 than all the numbers the 111 rundown creates will be triples too:
111: 333 444 555 666 777 888 999 000 111 222 333 (10)
The same issue will happen with doubles. When the starting number is 224 all the following numbers will be doubles too:
111: 224 335 446 557 668 779 880 991 002 113 224 (10)
And ultimately the same goes for singles as well, starting a single always create singles again.
While the 123 Rundown does not have this issue, it has another one: The digit 2. Like all rundowns that contain an even digit, that even digit only creates 5 different digits. So starting out again with 333:
123: 333 456 579 692 715 838 951 074 197 210 333 (10)
The center digits are 3 5 7 9 1 3 5 7 9 1 3. When the center starting digit is odd, every following digit with be odd too, the same goes for even digits.
Once you know this flaw you will realize very quickly that rundowns with only even digits are even more flawed, e.g. 248:
248: 333 571 719 957 195 333 (5)
Instead of 9 playable numbers Rundown 248 only creates 4 numbers.
But there are digits - besides the even digits 2 4 6 8 - that are even worse. The 5 only provides two options throughout a rundown. For example look at the last digit of the 135 rundown:
135: 333 468 593 628 753 888 913 048 173 208 333 (10)
The are only two options 8 and 3: 3 8 3 8 3 8 3 8 3 8 3. The worst would be a 555 rundown.
555: 333 888 333 (2)
Only one option here, actually the mirror of the initial number.
I do not even want to mention the most flawed digit, as you will all know that one: 0. As zero does not change anything the digit will be kept in every number of the rundown.
With 0, 2, 4, 5, 6, 8 flawed, at least to a certain extent, only 4 digits are left: 1 3 7 and 9. You also try to avoid and multiples, (see the 111 example) so you have exactly 24 options left:
137 139 173 179 193 197 317 319 371 379 391 397 713 719 731 739 791 793 913 917 931 937 971 973
Now you might want to cut out the ascending and descending ones and you end up with 16:
173 193 197 317 319 371 391 397 713 719 739 791 793 913 917 937
I personally did not want the numbers to start out or end with a 1 or a 9, because the first and last digits would be always ascending or descending.
So ultimately there were only 4 options left: 317 397 713 793
Do you see why 317 was picked? Right, it was the first one of the short list. And that's pretty much why the 317 rundown became so famous and not the other three (Even though they are just as flawless!). And the examples from before show just how flawless it is. Even if the most recent number is a triple e.g. 333 only one other triple will occur in the results (the mirror 888, you guessed it):
317: 333 640 957 264 571 888 195 402 719 026 333 (10)
Take a "normal" number e.g. 742 to start with and you can see singles and doubles will occur:
317: 742 059 366 673 980 297 504 811 128 435 742 (10)
A decent selection, and every digit in the selection (the start number included) occurs exactly 3 times, always.
That was a little lesson in regards to rundowns.Thanks Mike K.