All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars
 perplexus dot info

 Square Birthdays (Posted on 2007-11-29)
A date can be written as DD/MM/YY, so that for example 01/08/16 means 1 August 1916. But if you concatenate just the digits, 010816 happens to be a perfect square, as it is 104². Call such a day a "square day".

Adrian's grandfather was one of six cousins born on different square days in the same year, which was a leap year in the 20th century. All of them died on square days in leap years, and none of them lived to see age 99. Each of them except Adrian's grandfather died in the same month as his or her birthday.

What was Adrian's grandfather's date of birth?

 Submitted by Charlie Rating: 3.3333 (3 votes) Solution: (Hide) The numbers that are squares and can represent dates in any century and could be leap years (they're divisible by 4) are the following: ```240100 260100 230400 270400 220900 280900 300304 10404 200704 40804 121104 91204 60516 10816 110224 101124 20736 11236 150544 131044 80656 70756 20164 50176 30276 30976 51076 ``` Regardless of how you count centuries, both 1900 and 2000 are ineligible for the grandfather's year of birth, as 1900 was not a leap year and 2000 is too recent for a grandfather to have been born. Of the year-ending two digits remaining, only '04 has six separate dates for the six separate cousins. As 2004 is too late for a grandfather to have been born, it must have been 1904. March (i.e., month 03) is unique to that year (within the 99 years beginning then), while the other months' specified for that year recur in later 20th century years: April in 2000, July in 1956, August in 1916 (that cousin was almost 12 when he/she died, but he/she didn't need to be a grandfather), November in 1924 and December in 1936. So Adrian's grandfather was born 30 March 1904. From Enigma No. 1464 by Adrian Somerfield, New Scientist, 13 October 2007.

 Subject Author Date answer K Sengupta 2008-02-06 06:11:49 re(3): Do April Fools live longer? (SPOILER) brianjn 2007-11-30 03:37:41 re(2): Do April Fools live longer? (SPOILER) Dej Mar 2007-11-30 02:21:54 re: Do April Fools live longer? (SPOILER) brianjn 2007-11-30 00:49:23 re: Some Unanswered Questions brianjn 2007-11-29 18:10:53 Some Unanswered Questions brianjn 2007-11-29 17:34:36 Do April Fools live longer? (SPOILER) Dej Mar 2007-11-29 11:27:46

 Search: Search body:
Forums (0)