Which units would you choose best to fit these situations?
When measuring some property of an object the number we measure depends on the units chosen. For example, 1cm = 0.01m, so converting from cm to m makes the number get smaller; we need more small units to make up the number of big units. In each case below, does the number get bigger or smaller following a change in units? Can you estimate without a calculator an approximate factor by which the
numbers would change in each case?
Can you make up some of your own similar problems?
Try the fun Zin Obelisk task from the main NRICH site