akphidelt,
I'm interested. Why do you use a LEN function in this formula? I know
what LEN does, I just assume you are avoiding some issue by doing it
this way instead of a simple "$C$10". Why is that?

I'm not akphidelt, but did notice that the original post did not specify
that the entered values must be positive numbers. Using the LEN function
(instead of "$C$10") permits entered values to be positive or negative or
zero. If that's not the intent, change the formula accordingly.