Miscellanea Have you ever wondered when a parent will be exactly double your age or a child exactly half? If, like me, you have spent at least one family luncheon discussing this matter, you have come to the right place!
The formula is straightforward: to work out when A will be (or was) twice the age of person B, work out the age difference between A and B and add that amount of time on to B's birthday. Alternatively, work out the age difference between A and B and then add twice that amount of time to A's birthday. For example, if Rumpelstiltskin was born on 1st January 1950 and Rapunzel was born on 1st January 1990, the age difference is exactly 40 years; adding 40 years to 1 January 1990 gives 1 January 2030. Thus, Rumplestiltskin will be twice Rapunzel's age on 1 January 2030.
Of course, it all becomes somewhat harder to calculate when the birthdays are not both on 1st January. Therefore, this page provides a small program to work it out for you. Enter your birthday into the upper box (in the form "1 Jan 1950"), enter the birthday of the other person into the lower box (in the same format), and click the 'Calculate' button. The date on which the other person will be twice (or half) your age will be displayed on this page.