How do I mask a number

You can do that in the field option properties. Here's how:

1. Login to your account and open your form.
2. Select the field and click the Properties icon.
3. Go to the Options tab and enable the Input Mask.

Here's our guide: https://www.jotform.com/help/381-Getting-Started-with-the-Basics-of-Input-Masking

Please do get back to us if you have questions. Thank you.