System.Math

Provides static methods for common mathematical functions including trigonometric and logarithm functions

System.Math.Abs

Returns the absolute value of a number

Math.Abs() - absolute value 
Math.Abs(23.7) = 23.7 
Math.Abs(-23.7) - 23.7

Decimal absolutevalue; 
Absolutevalue = System.Math.Abs(10.5M);  // decimal 
Absolutevalue = System.Math.Abs(System.Convert.ToDecimal(10.5D));  // double

System.Math.Acos

System.Math.Asin

System.Math.Atan

Atan - returns the arctangent in radians of n

System.Math.Atan2

System.Math.BigMul

System.Math.Ceiling

Returns a number rounded up to the nearest integer.

Math.Ceiling() - rounds x to the smallest integer not less than x 
Math.Ceiling(9.2) = 10 
Math.Ceiling(-9.8) = -9 
Math.Ceiling(0) = 1.0

System.Math.Cos

Cos - returns the cosine of an angle. The angle must be expressed in radians

System.Math.Cosh

System.Math.DivRem

System.Math.E

public const double E = 2.7182818284590451;

System.Math.Exp

Returns the constant e raised to the power of the argument

Math.Exp() - exponential method

System.Math.Floor

Returns a number rounded down to the nearest integer.

Math.Floor() - round x to the largest integer not greater than x

System.Math.IEEERemainder

System.Math.Log

Returns the logarithm of a number to the base you specify.

System.Math.Log10

Returns the logarithm of a number to the base 10

System.Math.Max

Returns the largest number

System.Math.Min

Returns the smallest number

System.Math.Pi

public const double PI = 3.1415926535897931;

System.Math.Pow

Returns a number raised to the specified power.

System.Math.Round

Returns a number rounded to a specified number of digits

System.Math.Sign

Returns a value indicating the sign of a number.
returns -1 if n < 0 , 0 if n = 0 or =1 if n > 0