There are many different types of idiopathic headache with the pain in the back of the head, including epicrania fugax, nummular headache, cluster headache, and hemicrania continua. There is also a condition termed new daily persistent headache, which also belongs to this type and can cause a headache for several months.
Calculate Use: Multiply the number of pages per week (the average in a production environment is 100) by the number of weeks in a six-month period (26). A good estimate is that you will print 2,600 pages each six months. Now, take 2,600 and divide it by the number of pages the ink cartridge will print (225).
Pages vs. Time. Because printer manufacturers don't know how much you print, the primary cartridge life rating is in pages. For instance, a cartridge rated to yield 3,000 pages should last for approximately that number of pages. At the same time, many cartridges also have shelf lives.