7 ms·
Ask HN: Why do parking tickets across lots of cities follow a similar # pattern?
We noticed something interesting as we were looking at parking ticket numbers.
The sequence of parking ticket numbers follows a similar pattern across lots of different cities.
We thought it was because cities shared a similar software vendor... but it looks to be more extensive than that.
Anyone have any ideas why a large number of cities have the following parking ticket sequence:
827778501 (+11)
827778512 (+11)
827778523 (+11)
827778534 (+11)
827778545 (+11)
827778556 (+11)
827778560 (+4)
...and then continues to add '11' six times, and then adds a '4', and keeps repeating.
Is there a reason for this?
Is it a common sequence in other places too?
- madcaptenor 11y agoThe last digit may be a check digit. In particular, it might be the remainder upon dividing the number that the other digits make by 7. For example 82777850 divided by 7 leaves a remainder of 1. Some examples of this check digit scheme: http://nrich.maths.org/2036 http://nrich.maths.org/2036 http://www.cbp.gov/sites/default/files/documents/in_bond_check_1.pdf http://www.cbp.gov/sites/default/files/documents/in_bond_che... (with a clunky implementation) http://www.con-way.com/en/tools_pricing/freight/fr_tools/tracking/pro_number_check_digit_formula http://www.con-way.com/en/tools_pricing/freight/fr_tools/tra...
- davidhegarty 11y agoBINGO!!! You da man. That's seems to work for all my examples. Thanks!