Queen Elizabeth II acceded to the throne aged 25 following the death of her father King George VI on 6 February, 1952. On 9 September she will have reigned for 63 years and seven months.
The record for longest serving monarch had previously been held by Queen Victoria, having reigned for 23,226 days, 16 hours and 23 minutes.
Queen Elizabeth II to become Britain’s longest reigning monarch. I guess this story is meant to test its reader’s ability to convert dates from years/months to days/hours/minutes. Good thing WolframAlpha is around.