I have had issue with a formula producing a null value, I've narrowed it down to the exponential function, and have simplified to this:
Formula:
Date Type: Number
Decimal places: 15
Formula : 10^2
This is then assigned (Equals) to a variable:
Data Type: Number
Allow multiple values (collection) = FALSE
Decimal places: 15
Available for input: TRUE
Available for output: FALSE
I would expect it to return 100, so I assume I must have something wrong somewhere to get a NULL value. Any suggestions?
Andrew Russo (BACA Systems) 
Forum Ambassador
Bad news. i have your answer... You can only raise a number to the power of an integer.
^ (Exponentiation)
Description: | Raises a number to a power of a specified number. Use: | number^integer and replace number with a merge field, expression, or another numeric value; replace integer with a merge field that contains an integer, expression, or any integer. Example: | NumberOfEmployees^4 calculates the number of employees to the 4th power. Report Example: | ACTIVE:SUM ^ 2 calculates the number of active Salesforce users to the 2nd power for administration. This formula is a number data type that returns a positive integer. Tips: | Avoid replacing integer with a negative number.
https://help.salesforce.com/s/articleView?id=sf.customize_functions_a_h.htm&type=5
