Exponents in Computation Layer:

How do I check 6s^2 is correct in a table?

How do I check A=6s^2 is correct in a function box?

You have to check for each cell individually, but you can make a function (I use x so I don’t have to set extra parameters). Since you have set values in the first column:

SA= simpleFunction("6*x^2")
check1= this.cellNumericValue(1,2)=SA.evaluateAt(3)
check2= this.cellNumericValue(2,2)=SA.evaluateAt(5)
cellContent(1,3): when check1 "Check" otherwise "X"

Also, instead of a third column for feedback, you could use a cellSuffix in the second column.
cellSuffix(1,2): when check1 "Check" otherwise "X"

Thanks for your help how do I check the last row when the length of the side is “s”?

SA5= simpleFunction(`this.cellContent(5,2)`)
check5= SA5.evaluateAt(3)=SA.evaluateAt(3) 
               and SA5.evaluateAt(5)=SA.evaluateAt(5)

Basically, make a function from student entry, and see if evaluating it at a variety of values matches the expected SA.