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Math.Sqrt Method

Returns the square root of a specified number.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static double Sqrt(
	double d


Type: System.Double
A number.

Return Value

Type: System.Double
One of the values in the following table.

d parameter

Return value

Zero, or positive

The positive square root of d.



Equals NaN


Equals PositiveInfinity


The square root of the area of a square represents the length of any side of the square. The following example displays the area of some cities in the United States and gives an impression of each city's size if it were represented by a square.

using System;

public class Example
   public static void Main()
      // Create an array containing the area of some squares.
      Tuple<string, double>[] areas = 
                     { Tuple.Create("Sitka, Alaska", 2870.3), 
                       Tuple.Create("New York City", 302.6), 
                       Tuple.Create("Los Angeles", 468.7), 
                       Tuple.Create("Detroit", 138.8), 
                       Tuple.Create("Chicago", 227.1), 
                       Tuple.Create("San Diego", 325.2) };

      Console.WriteLine("{0,-18} {1,14:N1} {2,30}\n", "City", "Area (mi.)", 
                        "Equivalent to a square with:");

      foreach (var area in areas)
        Console.WriteLine("{0,-18} {1,14:N1} {2,14:N2} miles per side", 
                          area.Item1, area.Item2, Math.Round(Math.Sqrt(area.Item2), 2));        
// The example displays the following output:
//    City                   Area (mi.)   Equivalent to a square with:
//    Sitka, Alaska             2,870.3          53.58 miles per side
//    New York City               302.6          17.40 miles per side
//    Los Angeles                 468.7          21.65 miles per side
//    Detroit                     138.8          11.78 miles per side
//    Chicago                     227.1          15.07 miles per side
//    San Diego                   325.2          18.03 miles per side

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.