Translations:Using regular expressions/126/en
From LimeSurvey Manual
Numbers from 1 to 99999
/^([1-9]|[1-9][0-9]|[1-9][0-9][0-9]|[1-9][0-9][0-9][0-9]|[1-9][0-9][0-9][0-9][0-9])$/
/^[1-9][0-9]{0,4}$/ does the same as above but should run a little faster
Numbers from 1 to 999, 1.000 to 999.999 to 999.999.999
/^[1-9][0-9]{0,2}(?:\.[0-9]{3}){0,2}$/
Accepts numbers from 1 to 999, 1.000 to 999.999 to 999.999.999 but rejects numbers like 999.1.1 , 94.22.22, 999.1.22, 999.11.1, 999.1.333