Hi, We use Zoho CRM and want to auto populate a custom field like a serial number number that auto increments but is based off of several other custom fields. For example

SerialNumber=CustomField1+CustomField2+AutoIncrementNumber

Any ideas how to do this? I know I can create a field that auto increments based on this article - https://help.zoho.com/portal/en/kb/crm/faqs/product-customization/web-tabs/articles/how-to-create-an-auto-number-field 

but I can't figure out how to add in the other rules. 

Thanks