why is a number seven written with a line through it?

Question

I have been told its to do with the arabic people that created the numbering system. Is this true? (though obviously it can be mistaken for a 1 as well, so this is a sensible answer).

Answer 1

Two of your answerers so far are correct.

If you saw any French or German handwritten numbers, you would be amazed by the big upstroke at the beginning of their digit "1". It is usually half the length of the main downstroke, and sometimes a bit more. If they didn't put a line across the middle of their "7", you would never be sure which was which.

English and American people who have been at school or university in continental Europe often pick up this convention for 7, but not for 1. Early computer users who wrote out data on sheets, for other people to punch onto cards or paper tape, were also taught to do this to minimise punching errors.

Answer 2

Numeral Seven

Answer 3

The point is to distinguish it from the numeral for 1. And possibly from the Hebrew letter Zayin.

"As is the case with the European glyph, the Cham and Khmer glyph for 7 also evolved to look like their glyph for 1, though in a different way, and so they were also concerned with making their 7 more different. For the Khmer this often involved adding a horizontal line above the glyph. This is analogous to the horizontal stroke through the middle that is sometimes used in handwriting in the Western world but which is almost never used in computer fonts. This horizontal stroke is, however, important to distinguish the glyph for seven from the glyph for one in writings that use a long upstroke in the glyph for one."

Answer 4

Our numbering system is an Hindu invention but it was brought to Europe's attention by the Arabs. In many countriesof Europe , a small horizontal bar is added to distinguish 7 from 1. North Americans draw their 7s without that small bar, and their 1s without the little hook at the top

Answer 5

I didn't, but I have slipped into the habit of it. When you do algebra, its much easier to tell the difference between 7, Z, 2 that way (given my style of handwriting). I also put lines through Z. Theres a similar problem for 5 and S, and capital i, lower case L, and 1.

Answer 6

It's simply a number seven. Those dashed sevens are common in parts of europe, including where I grew up (Finland - and yes, I dash my sevens). The purpose of the dash is just to make sure your sevens aren't mistaken for ones.

I don't know where the dash originated, but I recall seeing ancient arabic numbers with no dashes, so it probably didn't come from there.

Answer 7

It is a fairly common practice in Europe, especially when the numeral 1 is written with a large top serif which could be confused with a 7. Digression: the Arabic digits that we know and love (?) are not used in Saudi Arabia -- they use Hindi digits instead.

Answer 8

From what I understand this is an eastern European was of writing the number seven. And the Arabic people didn't invent our number system, most of it comes from the classical Greek mathematicians.

Answer 9

I'm American and I write my sevens with a line through them.

Answer 10

Hi. The letter "Z" can be written this way also. The numbers "6" and "9" are sometimes written with a line UNDER them. Just for clarification in all cases.