很多同学在参加
+ plus
- minus
* 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
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