What is two plus two? Here are the answers given by ten-year-old school pupils over the last six decades:
'Four, of course.'
'I think it's three but it's the method that counts.'
'Just a second while I get our my calculator.'
'Just a second while I open a window on my PC and double-click on the Calculator icon.'
'Just a second while I check the addition home page.'
'Just a second while I check with my friends on MXit.'