







When is John's next birthday on a Friday? 
20190315 

From Darek: The question is the following:
Last Friday 4th of April of 2014 John was 40 years old. How old will John be the next time when his birthday fell on Friday?
Thanks for your help Answered by Penny Nom. 





The astronomers' calendar 
20001129 

From Show_Li: The calendar that astronomers use began on Jan. 1, 4713 B.C. on that day, the julian calendar, the lunar calendar, and roman tax system calendar all coincided. This won't happen again until 3267 A.D. (a). How many years ago was the astronomer's calendar started? (b). Find the number of years between times that the three calendars coincided. Answered by Penny Nom. 





Prime dates 
19990325 

From Jessica Brown: I'm asking how do you figure out all the prime numbers in a year and, whats the average amount of prime numbers per week. Answered by Jack LeSage and Penny Nom. 

