I am having trouble completing the following Trailhead: Create a formula field that determines the number of days between the end date of a contract and today. This is the formula that I am using:

EndDate - TODAY() 

I keep getting the following error when I check the syntax:  Error: Formula result is data type (Number), incompatible with expected data type (Date).

Trying to complete the "Create an approval process that validates when a Prospect Account becomes a Customer."

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, Account number must be 8 characters long.: [AccountNumber]

 

I receive this error when I check my challenge.


Challenge not yet complete... here's what's wrong: 
An account with a related opportunity did not calculate the correct potential value.

The task was to Create a rollup summary field that determines the potential value of the opportunities associated with an account.
Add a custom field to the standard account object that provides a rollup summary of the total expected revenue from all related opportunities.The rollup summary field should be labeled 'Potential Value' and have the Field Name of 'Potential_Value'. The resulting API name should be 'Potential_Value__c'.
The rollup summary should calculate the total expected revenue of all the opportunities related to the account.

Here is a snap shot of my work. Any suggestions as to why this is failing?



Thanks,
Darren