HTML calculator (probably dead simple)

[Skunkworks]

I’m after a simple calculator with 3 fields for height, width and length, and a dropdown for CM or MM. I need it to calculate how many whole 20cm cubes will fit into the space given.

I imagine this is one line of code.

Thanks.

 

[Skunkworks]

Sorry, should have mentioned, something I can paste into Dreamweaver.

I used to be able to do this stuff years ago.

 

[Skunkworks]

Edit: NVM, sorted now.