Determination of the day of the week possible to do all the calculations in one's head with a little practice). None of the methods given here perform range checks, so unreasonable dates will produce erroneous results. Every seventh day in a month has the same name as the previous: "Corresponding months" are those months within the calendar year that start on the same day of the week. For example, September and December correspond, because September 1 falls on the same day as December 1. Months can only correspond if the number of days between their first days is divisible by 7, or in other words, if their
Blue Monday (date) Blue Monday (date) Blue Monday is a name given to a day in January (typically the third Monday of the month) claimed to be the most depressing day of the year. The concept was first publicised as part of a 2005 press release from holiday company Sky Travel, which claimed to have calculated the date using an equation. It takes into account weather conditions and thus only applies to the Northern Hemisphere. The idea is considered pseudoscience, with its formula derided by scientists as nonsensical. This date was published in a press release under the name of Cliff Arnall, at