Restricting cells to numbers only
I noticed there's a way to restrict columns for most column types except Text/Numbers. I want to only allow numbers to be typed in and not letters because when letters are typed into those cells, it messes up all my formulas. More specifically, I'd like the editors to only be able to type in a range of numbers, for example only allowing numbers between 0-400,000. What is the best way to approach this?