Standard ANSI SQL92 supports the following first four basic arithmetic operators:
+
addition

subtraction
*
multiplication
/
division
%
modulo
The modulo operator determines the integer remainder of the division. This operator is not ANSI SQL supported, however, most databases support it. The following are some more useful mathematical functions to be aware of since you might need them. These functions are not standard in the ANSI SQL92 specs, therefore they may or may not be available on the specific RDBMS that you are using. However, they were available on several major database systems that I tested. They WILL work on this tutorial.
ABS(x)
returns the absolute value of x
SIGN(x)
returns the sign of input x as 1, 0, or 1 (negative, zero, or positive respectively)
MOD(x,y)
modulo  returns the integer remainder of x divided by y (same as x%y)
FLOOR(x)
returns the largest integer value that is less than or equal to x
CEILING(x) or CEIL(x)
returns the smallest integer value that is greater than or equal to x
POWER(x,y)
returns the value of x raised to the power of y
ROUND(x)
returns the value of x rounded to the nearest whole integer
ROUND(x,d)
returns the value of x rounded to the number of decimal places specified by the value d
SQRT(x)
returns the squareroot value of x
For example:
SELECT round(salary), firstname
FROM employee_info
This statement will select the salary rounded to the nearest whole value and the firstname from the employee_info table.