"Why do some people draw a line through the number 7?" The Newton Falls Public Library staff understood that our patron was curious as to why there was a line crossing the vertical line of that number.
Using the search words "why line through 7" brought up a variety of results. There were several different theories. At www.funtrivia.com, Carlos responded to this question, stating that "Mathematicians and computer data entrists are prone to crossing their sevens to differentiate from ones, and also their zeros to differentiate from the letter o." Other websites also noted that some people put a line through the letter Z, to ensure that it is not confused with the number 2.
The website, www.sciencechats.com directed us to an interesting slide show by Nzar Hama, an engineer in Sulimni, Kurdistan, Iraq. He states that "the numbers we write are made up of algorithms (1, 2, 3, 4, etc), called arabic algorithms . . . written in their primitive form . . ." they are made up of angles. The number one written with the small tall at the top has one angle. The other numbers, written in straight lines, is each made up of lines with the corresponding number of angles.