1. Navigate to Settings | Solutions | Packt.
2. Create two new fields by clicking on Entity | Contact | Fields | New as follows:
   • Start Date of type Date Time
   • End Date of type Date Time
3. Create a new Calculated field and enter the following details:
   • Display Name: Months for graduation
   • Data Type: Whole Number
   • Field Type: Calculated
4. Click on Edit next to the Field Type drop-down.
5. In the Calculated dialog under Condition (Optional), click on Add condition.

6. In the If row, enter the following details and click on the tick box:
   • Entity: Current Entity (Contact)
   • Field: Contact Type
   • Operator: Equals
   • Type: Value
   • Value: Student
7. Under Action, click on Add action, enter DIFFINMONTHS(packt_enddate, packt_startdate), and then click on the tick button:

8. Click on Save and Close on the rollup field dialogue and the attribute dialogue.