This shows the five units: kilometers squared, hectameters, meters squared, centimeters squared and millimeters squared in five bubbles. Arrows show that to change kilometers squared into hectameters, you multiply by 100; to change hectameters into meters squared, you multiply by 10,000; to change meters squared into centimeters squared, you multiply by 10,000 and to change centimeters squared into milimeters squared, you multiply by 100. Further arrows show that to convert milimeters squared into centimeters squared you divide by 100; to change centimeters squared into meters squared you divide by 10,000; to change meters squared into hectameters, you divide by 10,000 and to change hectameters into kilometers squared, you divide by 100.

10.6.7 Estimating Areas