# Why is . (full stop) is used for multiplication?

I'm from Turkey and here I often see people use full stop for multiplication sign. I see them on hand written papers, on digital texts, even on printed books. This feels so weird for me (even though I live here).   There's an institution here called "Türk Dil Kurumu" (Turk(ish) Language Instution) that regulates the changes to Turkish, etc. Even on the page of that instution, the use of full stop (in addition to x) as the multiplication sign is promoted.

I started programming six years ago, and probably that's the reason I don't feel comfortable using full stop as multiplication. I started using * (asterisk) on digital texts, × (\times) and · (interpunct) on word processors, but never full stop. (I also use dot as the decimal seperator in contast to the country I live in).

Another thing (deviation?) to consider is that the decimal seperator is comma, not dot. This might be related to the choice of multiplication sign. If that's the case, then I'm curious what do the countries that use comma as the decimal seperator use for multiplication sign? If they also use full stop as the multiplication sign, how many countries are there? Is there a reason for it? If so, what is it? Is it just historical?

My only consolation is that some other instutions follow the international pattern (assuming the use of ×, ·, * is international; if not, it should be). One of them is ÖSYM (Student Selection and Placement System). It uses interpunct as the multiplication sign. Though, I'm not sure if the choice of interpunct here is intentional. Since foreign students also take these tests, the choice might be obligatory. Nevertheless, it's a change in the right direction.

I also saw another question about this, but I'm not satisfied with the answers, and I think mine has more depth to it. So I'm gonna post it anyway.

• It isn't used in formal mathematics. Only poor rendering with limited tools uses it. Sep 28, 2018 at 12:51
• "If that's the case, then I'm curious what do the countries that use comma as the decimal seperator use for multiplication sign?" Tiny answer to this: in Dutch, the decimal separator is a comma, and I rarely to never see someone use a . as a multiplication symbol. However, we use periods to separate thousands: so a number like $10^{10}$ would be rendered $10.000.000.000$. Sep 28, 2018 at 12:51
• We generally use the \cdot (latex notation) such as in $2\cdot 3$. Sep 28, 2018 at 13:01
• Sep 28, 2018 at 13:10
• According to Cajori (vol. 1, page 267): The dot was introduced as a symbol for multiplication by G.W. Leibniz. On July 29, 1698, he wrote in a letter to John Bernoulli: "I do not like $\times$ as a symbol for multiplication, as it is easily confounded with $x$; ... often I simply relate two quantities by an interposed dot and indicate multiplication by $ZC \cdot LM$. Hence, in designating ratio I use not one point but two points, which I use at the same time for division." Sep 28, 2018 at 13:17