# C# | Math.Log10() Method

Last Updated : 31 Jan, 2019

In C#, Math.Log10() is a Math class method. It is used to return the base 10 logarithm of a specified number.

Syntax:

`public static double Log10(double val)`

Parameter:

val: It is the specified number whose logarithm to be calculated and its type is System.Double.

Return Value: It returns the logarithm of val(base 10 log of val) and its type is System.Double.

Note: Parameter val is always specified as a base 10 number. The return value is depend on the argument passed. Below are some cases:

• If the argument is positive then method will return the natural logarithm or log10(val).
• If the argument is zero, then the result is NegativeInfinity.
• If the argument is Negative(less than zero) or equal to NaN, then the result is NaN.
• If the argument is PositiveInfinity, then the result is PositiveInfinity.
• If the argument is NegativeInfinity, then the result is NaN.

Example:

 `// C# program to demonstrate working ` `// of Math.Log10(Double) method ` `using` `System; ` ` `  `class` `Geeks { ` ` `  `    ``// Main Method ` `    ``public` `static` `void` `Main(String[] args) ` `    ``{ ` ` `  `        ``// double values whose logarithm  ` `        ``// to be calculated ` `        ``double` `a = 4.55; ` `        ``double` `b = 0; ` `        ``double` `c = -2.45; ` `        ``double` `nan = Double.NaN; ` `        ``double` `positiveInfinity = Double.PositiveInfinity;      ` `        ``double` `negativeInfinity = Double.NegativeInfinity; ` ` `  `        ``// Input is positive number so output ` `        ``// will be logarithm of number ` `        ``Console.WriteLine(Math.Log10(a)); ` ` `  `        ``// positive zero as argument, so output  ` `        ``// will be -Infinity ` `        ``Console.WriteLine(Math.Log10(b)); ` ` `  `        ``// Input is negative number so output ` `        ``// will be NaN ` `        ``Console.WriteLine(Math.Log10(c)); ` ` `  `        ``// Input is NaN so output ` `        ``// will be NaN ` `        ``Console.WriteLine(Math.Log10(nan)); ` ` `  `        ``// Input is PositiveInfinity so output ` `        ``// will be Infinity ` `        ``Console.WriteLine(Math.Log10(positiveInfinity)); ` ` `  `        ``// Input is NegativeInfinity so output ` `        ``// will be NaN ` `        ``Console.WriteLine(Math.Log10(negativeInfinity)); ` `    ``} ` `} `

Output:

```0.658011396657112
-Infinity
NaN
NaN
Infinity
NaN
```