I want to increment the value of custom field called BillingUpdate__c(number datatype) of Account object, whenever any value of the Billing Address of the Account object gets updated.
Use the above as the field value for the Update
1)Note the workflow you create must be every time the record is created or edited
2)Use the criteria such that any one of the fields i have used in above formula is not null.(following best practice and not allowing this rule to simply run).
3)Please keep default value as 0 for the BillingUpdate__c field .
Create a workflow rule on Accout object that gets triggered when Billing Address is updated. Associate a field update with this workflow rule which will set the custom field value to whatever you want it to be.