Number validation: Cannot start or end with zero

You can use a regular expression for validation:

^([1-9]d{0,4}[1-9]|d)$

Thank you for the reply. I am looking at this and I am sure it makes sense but I am confused as to how to apply it to my situation.

Use the following settings for single line text control in Nintex Forms:

When I enter that expression my form crashes:

Here is my screen

You have an extra ) added after 1-9]) <----

 ^([1-9])d{0,4}[1-9]|d)$

 ^([1-9]d{0,4}[1-9]|d)$

Ah Ha!  Thx. Will clean up.

That was it! Thanks

‌ - Big thanks to you for getting this going and solved.

Sorry, please change ^([1-9]d{0,4}[1-9]|d)$ to ^([1-9]d{0,4}[1-9]|[1-9])$

This ensures that numbers with only one digit may not have the value 0.

What is a good resource to reference this syntax so I can learn and build upon it?

there are so many tutorial sites for regular expressions. See Regex Tutorial—From Regex 101 to Advanced Regex , play with online tester Online regex tester and debugger: PHP, PCRE, Python, Golang and JavaScript and check Microsoft docu for .NET regular expressions.

TY