GRE数学基础进阶知识：数学符号

+ plus ;positive

- minus ;negative

× multiplied by ;times

÷ divided by

= equals

≈ approximately equals

≠ not equal to

less than

greater than

≤ equal to or less than

≥ equal to or greater than o

( ) round brackets ;parentheses

[ ] square brackets

{ } braces

∈ is a member of the set

? is a subset of

∽ similar to

≌ congruent to

* denotes an operation

∴ therefore

∵ because

∶ ratio sign, divided by, is to

∷ equals, as(proportion)

∥ parallel to

⊥ perpendicular to, at right angles with

∠ angle

∟ right angle

o degree

′ minute

″ second

⊙ circle

A?B arc AB

e the base of natural logarithms,approx.2.71828

x! factorial x, x(x-1)(x-2)---1

lognx log x to the base n

π pi

lnx log x to the base e(natural logarithm)

lgx log x to the base 10(common logarithm)

|x| the absolute value of x