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 20^th 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?

(In reply to Do April Fools live longer? (SPOILER) by Dej Mar)

NOTE:
The following comment:

"While I did concur with your result I contend that 538² does not yield the result that you claim; though my programmed offering says different my calculator is agreement with me too."

            no longer applies (see following comment).

Edited on November 30, 2007, 2:41 am

Posted by brianjn on 2007-11-30 00:49:23