"Subtract 8 days, 23 hours and 31 minutes from 29 days, 15 hours and 7 minutes.
"If HMFL spells JOHN in a particular code, how does that code work?
"Four men, Smith, Robinson, Jones and Brown, all grow vegetables. All four grow lettuce. All but Smith and Robinson grow potatoes. Smith and Brown grow cabbages. Robinson grows peas. Which two vegetables does Robinson grow? Which two does Smith grow? Which man grows Potatoes, lettuce, cabbage, but no peas?"
For 2½ hours, one day last week, 32,000 little Londoners, aged 10½ to 11½, sat at their school desks puzzling over such questions as...