For a study I am doing everyone gets assigned a unique number. All unique numbers are divisble by 11 (this is done because it makes sequential numbers quite different from each other).
I would ideally like a regex which I can use to check that the number entered in the study_id field is an acceptable value - e.g divisible by 11. I will have leading zeroes to a maximum of 5 digits So:
Any suggestions gratefully received
This isn't possible because there are no textual similarities between numbers that are divisible by 11. Regex is used for text matching.
For example 000165 is divisible by 11 as is 00011.
The best way to validate the number is to divide it by 11 and see if there is any remainder. So in Excel you'd do this:
=IF(MOD(165, 11) = 0, "VALID", "INVALID")
Or C# you'd do something like this
bool isValid = 165 % 11 == 0;
(Disclaimer I'm not familiar with ODK so I can't provide a suitable sample; I've just guessed on the best language to write in)