# Enumerable.Sum Method (IEnumerable(Of Nullable(Of Single)))

.NET Framework 4.5

Computes the sum of a sequence of nullable Single values.

Namespace:  System.Linq
Assemblies:   System.Linq (in System.Linq.dll)
System.Core (in System.Core.dll)

## Syntax

```'Declaration
<ExtensionAttribute> _
Public Shared Function Sum ( _
source As IEnumerable(Of Nullable(Of Single)) _
) As Nullable(Of Single)
```

#### Parameters

source
Type: System.Collections.Generic.IEnumerable(Of Nullable(Of Single))

A sequence of nullable Single values to calculate the sum of.

#### Return Value

Type: System.Nullable(Of Single)
The sum of the values in the sequence.

#### Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(Of Nullable(Of Single)). When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

## Exceptions

ExceptionCondition
ArgumentNullException

source is Nothing.

## Remarks

This method returns zero if source contains no elements.

The result does not include values that are Nothing.

In Visual Basic query expression syntax, an Aggregate Into Sum() clause translates to an invocation of Sum.

## Examples

The following code example demonstrates how to use Sum(IEnumerable(Of Nullable(Of Single))) to sum the values of a sequence.

```        ' Create an array of Nullable Single values.
Dim points() As Nullable(Of Single) = _
{Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}

' Get the sum of values in the list.
Dim sum As Nullable(Of Single) = points.Sum()

' Display the output.
MsgBox("Total points earned: " & sum)

' This code produces the following output:
'
' Total points earned: 311.39
```

## Version Information

#### .NET Framework

Supported in: 4.6, 4.5, 4, 3.5

#### .NET Framework Client Profile

Supported in: 4, 3.5 SP1

#### XNA Framework

Supported in: 3.0

#### Portable Class Library

Supported in: Portable Class Library
Supported in: Windows Phone 8.1
Supported in: Windows Phone Silverlight 8.1
Supported in: Windows Phone Silverlight 8