How big is a square meter?

Answer 1

-- Its area is 1 square meter.

-- Its volume is zero.

-- It's impossible to tell how long or wide it is, or even what shape it is.

-- The distance all the way around it has to be at least 3.545 meters.

Answer 2

A square meter contains ten thousand square centimeters inside of it, or one million of square milimeters.