Question

What is the length in millimeters of a crystal of copper sulfate that is 0.250 inch long?

Answer 1

`1` `"inch"` `=` `25.4` `mm`.

Explanation:

So, `0.25` `"inches"` `xx` `25.4` `mm*"inch"^-1` `~~` `6` `mm`. This is a big, macroscopic crystal.

I am reminded of Cockney rhyming slang where `"half-inch"` means `"pinch"`, to rob someone. "Here, someone's half-inched my wallet!"