How High Is Mount Everest In Km2? (Kilometres Squared)

Unfortunately, height, or elevation, is not measured in squared units.  Squared units are for measuring area, that is to say, the amount of 2-dimensional space an object or piece of land takes up.

For example:  Houses are measured in square feet.  This relates to not how tall the house is, but how much floor space it has.  One house might be 1300 ft2 (square feet) or another might be 10,000 ft2 (which is a darn big house!).

The lot that a house is on is also measured in square feet (and, more typically, acres; one acre=43560ft2).  Some lots have only 10,000ft2, others might have 346,281ft2.  But, this is only a measurement of area.  It is a measurement of how much space, on a flat plane (a plane consisting only of length and width--2 dimensions) a given piece of land takes up.

So, I ask you, is this really what your teachers asked: How high is Mt. Everest in Km2?  They didn't ask how much area Mt. Everest takes up in Km2?  If they did truly ask how high the mountain is in Km2, then that is truly a bad question, with all due respect to your teachers.