68
95
99........

The 1st 3 standard dev from the mean......................w/o their dec's............truncated.......a imp. process in all this....................................95 and 99.................3 nines............3/9 = 1/3................1/3 = 0.33...........2/3 = 0.66........................................

Imp...................b/c the square root of 13.....starts out.....3.60...........like 360............the number of degrees in a full circle..............................if the glass is 1/3rd full..........it is 2/3rd empty................

1/3 = 0.33
2/3 = 0.66.............................vertically................two 36's..........like full circle.........truncated.......like 17 + 19 = 36.............................

68–95–99.7 rule - Wikipedia

https://en.wikipedia.org/wiki/68–95–99.7_rule

1. Cached
2. Similar

In statistics, the 68–95–99.7 rule is a shorthand used to remember the percentage of values that lie within a band around the mean in a normal distribution with a width of two, four and six standard deviations, respectively; more accurately, 68.27%, 95.45% and 99.73% of the values lie within one, two and three standard ...