general range function in vba

Hey forum , first time posting . I am working on a project in excel that replicates suduko . I am having trouble coming up with a function that checks a 3 x 3 area and checks if all the numbers add up to 45.
so the start should be {Function checkRange (rng as Range) As boolean} . So i just want a function that could highlight an area and it tell me if all the cells in there add upto 45 and return true or false in the cell which holds the formula. I just started vba 2 days ago so i am pretty lost .

thanks for your time forum

Hey so i got the formula to work , i used a different method

now my next problem is i have to have a subroutine using this formula that checks each row and column of the suduko puzzle and will change the background colour to something other white if the sum value is not 45. I already made the function "checkRange" that shows true or false if an area does not meet criteria. So how would i incorporate this into the subroutine ?