arc (as in ) add; plus; positive subtract; minus; negative plus or minus multiply; times; cross multiply; times divide divide by (as in ) angle circle cube root divide nth root parallelogram rectangle square root triangle ... between two symbols or at the end of a sequence or series to denote omission line AB ray AB line segment AB vector AB perpendicular is similar to not (when used as a connective) is congruent to (in figures) is congruent to (in numbers) therefore as is to (as in proportions such as a:b = c:d) $ dollar sign cent sign repeating decimal 1.444. . . || parallel degree degree Celsius degree Fahrenheit = equals is not equal to < is less than > is greater than < is less than or equal to > is greater than or equal to is approximately equal to intersection union; join empty set { } encloses a set is a subset of is not a subset of [ ) half-closed interval ( ] half-open interval [ ] closed interval % percent |a| absolute value of a ! factorial foot or minute inch or second infinity (x,y) coordinates of a point on a plane (x,y,z) coordinates of a point in space ( ) shows order of operations, as in (1+2)×4 = 3×4 = 12 pi (approximately 3.1415926) e the base of natural logarithms (approximately 2.71828183)