Question

Is the area of a key on a calculator 6.5 mm^2 , 65 mm^2 or 0.65 cm^2?

Answer 1

65
`mm^2` or 0.65
`cm^2` which are exactly the same area

Explanation:

Notice that 65
`mm^2` is exactly the same as 0.65
`cm^2`.

The most likely answer is 65
`mm^2`, since 8 mm by 8 mm is a reasonable size for a square shaped key of a hand-held calculator to fit a human finger.

The answer 6.5
`mm^2` is an area too small (about a square 3 mm by 3 mm which is to small for a human finger. It would be more appropriate for a pen or point of some type.