Rounding Down to a Number Divisible by 3?

I working on a dynamic drawer box component. It is designed so after the user enters dimensions of the opening and the cabinet depth, the drawer box is resized with the required clearance for the drawer glides. The drawer glides are available in 3" length increments so depth of the box–LenY–needs to be rounded down from the depth of the case to a number divisible by 3.

Could someone suggest a formula for that?

The Floor function has an optional (I think) second parameter “significance” which makes it easy:

Excellent! That seems to work just fine. Thank you.

Would ROUND(LenY,0) be better? I mean, if someone enters 5.99 inches, Floor would still give you 3 inches and round would give you 6 inches.

Another option, you can give a drop down list of lengths. It can’t be that many entries of 3 inches apart for the range of a drawer.


In the original post, @DaveR specified that he had to round down.

It would be hard to get a drawer that is 6 in. long to fit into a cabinet that is less that 6 in. deep. As Steve pointed out, I need to round down.

A drop down list could work but the drawer box gets used in projects that aren’t always standard depths. The component is designed to create drawer boxes that work with a specific range of drawer glides and it outputs ordering information to match what a specific drawer box maker uses to quote prices. Kind of limited use and so far, I’m the only one using it.

Hard but not impossible :wink: