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