I was intrigued by the item in the Trinity 2013 edition of Oxford Today describing Prof. Trefethern's reconfiguring of the calculation for working out one's BMI. Would you be able to explain to me – I read History – how, with an ordinary calculator, one computes one's “height in metres raised to the power of 2.5”? It is not, I assume, the same as simply multiplying it by 2.5.