Take the year in which you were born. From that date, subtract your current age. That's your mirror year. Your birth was as close to that date as to today's date. It seems a bit obvious until you start doing the calculations.
Seeing how distant your mirror year is, you sense afresh how much history you have lived through. Your average baby-boomer (hello!) who probably thinks of the Second World War as history, was born as close to the 1880s as to today. But it can be pretty shocking for quite young people too.
At History Today, Chris Lowry works out some of the implications.
