Most of us have little trouble working out how many milliliters are in 2.4 liters of water (it's 2,400). But the same can't be said when we're asked how many minutes are in 2.4 hours (it's 144).

Ray Norris wrote recently that he thought some academic researchers were unaware of the diversity of Aboriginal ways of counting. As part of his argument he examined a paper I wrote with a former ...