Symbols:Arithmetic and Algebra

$$+$$

"Plus", or "added to". A binary operation on two numbers or variables.

See Set Operations and Relations and Abstract Algebra for alternative definitions of this symbol.

$$-$$

"Minus", or "subtract". A binary operation on two numbers or variables.

See Set Operations and Relations and Logical Operators for alternative definitions of this symbol.

$$\times$$

"Times", or "multiplied by". A binary operation on two numbers.

Usually used when numbers are involved (as opposed to letters) to avoid confusion with the use of "$$\cdot$$" which could be confused with the decimal point.

The symbol $$\times$$ is cumbersome in the context of algebra, and may be confused with the letter $$x$$.

See Set Operations and Relations and Vector Algebra for alternative definitions of this symbol.

$$\cdot$$

$$x \cdot y$$ means $$x$$ times $$y$$, or $$x$$ multiplied by $$y$$, a binary operation on two numbers.

See Vector Algebra, Group Theory and Logical Operators: Deprecated Symbols for alternative definitions of this symbol.

$$\pm$$

"Plus or minus. $$a \pm b$$ means "$$a + b$$ or $$a - b$$", often seen when expressing the two solutions of a quadratic equation.

See Numerical Analysis for an alternative definition of this symbol.

$$\sum$$

"Sum". $$\sum_{i=a}^{n} x_i$$ is the addition of the elements of the sequence $$x_i$$ for $$i$$ from $$a$$ to $$n$$ (inclusive).

$$\prod$$

"Product". $$\prod_{i=a}^{n}$$ is the multiplication of the elements of the sequence $$x_i$$ for $$i$$ from $$a$$ to $$n$$ (inclusive).

$$\not=, \not>, \not<, \not\geq, \not\leq$$

"Negation". The above symbols all mean the opposite of the non struck through version of the symbol.

For example, $$x \not= y$$ means that $$x$$ is not equal to of $$y$$.