Mental Floss

Brain Game: Calculating Calendars


A publisher named George printed monthly calendars to give away to his customers, but he soon grew tired of changing all the dates around for each subsequent month. So he designed a basic calendar body that displayed nothing but the days of the week and the date numbers. It looked like this:

calendar.gif /

"Great," George thought. "Now I just have to make a printing plate for each possible month. When it's time to print the next month's calendar, I'll simply grab the necessary plate, add the month name and year at the top, and I'll be done." Unfortunately, this plate-making job proved more daunting than he anticipated.

How many different plates did George have to make? And why?

HERE is the answer.

ANSWER: 28 different plates. He'd need seven plates for 31-day months (with the first day of the month on different weekdays), another seven plates for 30-day months, and another seven plates for February's 28 days. He'd also need an additional seven plates for leap year Februarys, which have 29 days.