Your company sells cylindrical hyperbaric chambers. You need a formula field that calculates the volume of a cylinder for you, rounded to the nearest whole number, given its radius and height. Use the existing mathematical formula for the volume of a cylinder, V = πr2h, where r is the radius of the cylinder, h is the height, and π is the constant Pi. Note: Although this formula field might best be created on a custom object, for simplicity, we’ll create this formula on the Opportunity object.
>Create 2 custom fields of type Number on the Opportunity object: ‘radius’ with a resulting API name of ‘radius__c’ and ‘height’ with a resulting API name of ‘height__c’.
>The formula should be named ‘Cylinder Volume’, with the resulting API name ‘Cylinder_Volume__c‘ and should be created on the Opportunity object.
>The formula should reference the custom fields ‘radius__c‘ and ‘height__c‘.
>The formula should use 3.14159 as an approximation of Pi.

Heres the challenge that im stuck on. i have created the 2 custom fields. What im stuck on is where do we create the formula. Do we put it in the custom fields or is there another place u insert it?

thanks if anyone can help
 

• Create an OData 2.0 External Data Source named 'Mobile Devices' using the following URL: https://phone-odata-demo.herokuapp.com/devices.svc/
• Use the 'AtomPub' format and the 'Anonymous' Identity Type for the 'Mobile Devices' External Data Source.
• The 'Mobile Devices' data source must validate and sync the 'phone_plans' table to result in an external object with the API name 'Phone_Plan__x'.
• The 'Mobile Devices' data source must validate and sync the 'phones' table to result in an external object with the API name 'Phone__x'.
• Note that you will need to adjust the Object Names for the two external objects from the default setting after the initial sync.

all the thing have been done but i am getting following errorwhile checking challenge.