JMathLib understands the basic operators +,-,*,/,^ and !.

> 2+3
5.0
> 5!
120.0
> 2*3
6.0
> 2^3
8.0
> 2/3      
0.6666666666666666                

The operators work in the following order

^

* /

+ -

!

This can be modified by using brackets

> 2+3*4
14.0

> (2+3)*4
20.0

> 2*3^2
18.0

> (2*3)^2
36.0

> 2^3!
40320.0

> 2^(3!)
64.0

> 2+3!
120.0

> 2+(3!)
8.0