Talk:Multiplication

message: The middle dot is standard in the United States, the United Kingdom, and other countries where the period is used as a decimal point
Well, from my experience it's not true. Back in Poland, since the primary school, I'd been, like everyone else, taught to use the middle dot. We use the comma as the decimal mark. Now I study at an English university and it's English lecturers who use the period as the multiplication symbol. I had not even known the period could be used like this before I came here. So it doesn't look like the middle dot is standard in the UK. Ustt (talk) 12:05, 27 November 2013 (UTC)
replies: text: I went to school in Hungary. We never, in no circumstances use low period to denote multiplication. Middle dot is taught for multiplication sign. Alternatively, no sign between numbers and variable letters, or two variable letters, means multiplication. The × cross is used outside maths and physics literature. We understand period as a thousands separator although the official thousands separator is whitespace, so printed media would use whitespaces, not points. Decimal point is comma. Dot as decimal point is only accepted or used in computing in Hungary. --2A00:1028:8386:EC12:D8EE:B92:42E2:11F5 (talk) 10:02, 8 January 2021 (UTC)
replies: text: I've updated the page. The documented behavior (middle dot as decimal) is archaic, but still seen in some older journals and eg the history dept of cambridge university. See Interpunct and Decimal Separator for more info, but the TLDR is, the UK is not out of step with the rest of the planet on this: since 1968 we use the SI system, which mandates either a period or a comma as the decimal separator. --207.191.44.146 (talk) 18:29, 5 November 2021 (UTC)
thread_title:  Middle dot vs. period 

message: Why is the x figure called a cross?  This is not what the lay person thinks of when reading the word cross.  Technically, I guess it is a saltire, but that word's is too arcane (Wikipedia even marks it as wrong as I write it).  Is "ecks" really not what it is?  Certainly as kids learning multiplication we considered it "ecks"/"ex".211.225.33.104 (talk) 09:33, 9 July 2014 (UTC)
replies: text: I like the idea of calling it a saltire, though I don't usually think of a saltire as crossing at a 90° angle. Unschool 07:28, 10 November 2015 (UTC)

text: When you need to distinguish the letter x from the operator ×, it is a bad idea to call × an ex, ecks, x figure or such. It _actually_ is a cross. A special kind of cross. If you want to specify which cross it is then say, the multiplication sign. Saltire is a word that calls for a dictionary. --2A00:1028:8386:EC12:D8EE:B92:42E2:11F5 (talk) 09:46, 8 January 2021 (UTC)
thread_title:  Saltire 

message: A discussion is taking place to address the redirect :Multiplikand. The discussion will occur at Wikipedia:Redirects for discussion/Log/2021 April 9#Multiplikand until a consensus is reached, and readers of this page are welcome to contribute to the discussion.  Regards, SONIC678 00:00, 9 April 2021 (UTC)
thread_title:  "Multiplikand" listed at [[Wikipedia:Redirects for discussion|Redirects for discussion]] 

message: A discussion is taking place to address the redirect :Multiplikator. The discussion will occur at Wikipedia:Redirects for discussion/Log/2021 April 9#Multiplikator until a consensus is reached, and readers of this page are welcome to contribute to the discussion.  Regards, SONIC678 00:00, 9 April 2021 (UTC)
thread_title:  "Multiplikator" listed at [[Wikipedia:Redirects for discussion|Redirects for discussion]] 

message: the method noted as used in Germany (and often used now in the US) is also found in George Berkeley’s Arithmetica (1707) - was this amongst its first appearances in an English text? ELSchissel (talk) 02:04, 25 March 2022 (UTC)
thread_title:  In the history of methods of finding products 

message: I never learned TeX or LaTeX, so perhaps the following critique of the section  is way off base but, if I've misunderstood it, a clarification is surely needed to accommodate readers like me.
The claim, as I understand it, is:
:If the real number a is the least upper bound of a set A of rational numbers and the real number b is the least upper bound of a set B of rational numbers, then their product a⋅b is the least upper bound of the set C of rational numbers that consists of all the products of a rational number in A and a rational number in B.
However, if A contains a negative number such as −1 and B is not bounded below, then the set C will not be bounded above; it will have no upper bounds and hence no least one.
What am I missing?
Peter Brown (talk) 03:37, 7 February 2023 (UTC)
replies: text: Good catch. The previous text omitted to say that  and  were supposed positive. I have rewritten the section for fixing this and making the link with infinite decimals. D.Lazard (talk) 17:06, 7 February 2023 (UTC)
replies: text: Got it! Thanks.Peter Brown (talk) 17:27, 7 February 2023 (UTC)
thread_title:  Defining the product of real numbers 

message: — Assignment last updated by Ahlluhn (talk) 00:57, 31 May 2024 (UTC)
thread_title: Wiki Education assignment: 4A Wikipedia Assignment

message: The summation definition in the natural numbers is incomplete. The case when r=1 needs to be included. 75.191.107.254 (talk) 13:09, 27 April 2024 (UTC)
replies: text: It is included, as \sum_{j=1}^r s = \underbrace{ s+s+\cdots+s }_{r\text{ times}} reduces, when , to \sum_{j=1}^1 s = \underbrace{ s+s+\cdots+s }_{1\text{ times}} =s. This is included in the definition of capital-sigma notation. D.Lazard (talk) 13:39, 27 April 2024 (UTC)
thread_title:  Definition in Natural Numbers