# Math.Sqrt Method (Double)

.NET Framework (current version)

Returns the square root of a specified number.

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

## Syntax

```public static double Sqrt(
double d
)
```

#### Parameters

d
Type: System.Double

The number whose square root is to be found.

#### 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.

Negative

NaN

Equals NaN

NaN

Equals PositiveInfinity

PositiveInfinity

## Examples

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("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
```

## Version Information

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1