What does the dot mean in math?

Answer 1

There are several different meanings which depend on the context. I can think of at least four:

1. A dot (the decimal point) is used in decimal numbers to separate the integer part of a number from the fractional part. It can, of course be used similarly for numbers in other bases;
2. Many European countries use a dot as a thousand separator (and use a comma for the decimal "point") - the opposite of the UK and US usage;
3. A dot, in algebra, can represent simple multiplication (avoid confusion with the variable, x);
4. In vector algebra, a dot product is the scalar product of two vectors. For example, the dot product of the vectors (a,b,c) and (x,y,z) is ax+by+cz.

Answer 2

If it is a dot like a full stop used in literature then it is a decimal place. If it is a dot above a number after a decimal place it is a sign that shows recurring numbers for example 10/3=3.33333333333333333333333333 etc or just 3.3 reoccurring.

If it is a normal dot (.) then it is used as a decimal point, example 4.9. If it is a dot above a number after the decimal point, it is to show that the number is occurring again and again, which is also known as reoccurring.

There is also the dot product (or scalar product) of two vectors (a and b) which is represented by a dot:

a . b

Answer 3

A dot is used over a digit after a decimal point to represent a recurring digit, eg a dot over the 6 of 0.16 would mean the recurring decimal 0.1666... (the decimal representation of 1/6). If more than one digits repeat (eg 0.142857142857...) then a dot would be placed over the first digit of the repeating sequence, and a dot over the last digit (in 0.142857142857... it would be written as 0.142857 with a dot over the 1 and a dot over the 7).

Three dots in a row are often used similarly to the English ellipsis to show skipped items, eg 1 + 2 + ... + 9 is shorthand for 1 + 2 + 3 4 + 5 + 6 + 7 + 8 + 9, ie they are showing a similar pattern exists; They can also be used to show the pattern continues on, eg Σ 1/r² where r = 1, 2, 3, ... means the sum 1/1² + 1/2² + 1/3² + 1/4² + 1/5² + and so on with r taking each value of the counting numbers {1, 2, 3, ...}.

Answer 4

The two main uses are '1 to separate a number from its decimals#e.g. 123.45

& '2' to indicate a decimal goes to infinity e.g. 1.222334455.... ( N ote the trailing dots).

Do NOT confuse with the use of a comma. Commas are used to separate large numbers into thousands ( x 3) e.g 1,234,456

So you can have a number which uses both dots and commas. .e.g. 1,234,456.789....