What is the square root of 1000?

Go 250 units of distance in any one direction. Turn 90 degrees clockwise and go 250 units of distance in a straight line.

Turn 90 degrees clockwise and go 250 units of distance in a straight line.

Turn 90 degrees clockwise and go 250 units of distance in a straight line.

You will have travelled along a square route whose total distance was 1000 units of distance.

Alternatively you could have turned counter clockwise each time.