# What Is a Double Data Type in VB?

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Scott Campbell

The Double data type in Visual Basic (VB) is a fundamental data type that represents double-precision floating-point numbers. It is used to store decimal values with a higher range and precision compared to the Single data type.

## Understanding Double Data Type

The Double data type is commonly used when working with numbers that require a high degree of precision, such as scientific calculations, financial calculations, or any situation where accuracy is crucial.

In VB, the Double data type can store values ranging from approximately -1.79769313486232E+308 to -4.94065645841247E-324 for negative values, zero, and positive values up to approximately 4.94065645841247E-324 to 1.79769313486232E+308.

## Declaring and Assigning Double Variables

To declare a variable as a Double, you can use the following syntax:

``````
Dim variableName As Double
``````

You can also assign an initial value while declaring the variable:

``````
Dim pi As Double = 3.14159
``````

You can assign or change the value of a Double variable using the assignment operator (=):

``````
pi = 3.14159265358979
``````

## Performing Arithmetic Operations with Doubles

The Double data type supports all basic arithmetic operations such as addition (+), subtraction (-), multiplication (*), and division (/). Here’s an example:

``````
Dim num1 As Double = 10.5
Dim num2 As Double = 5

Dim sum As Double = num1 + num2
Dim difference As Double = num1 - num2
Dim product As Double = num1 * num2
Dim quotient As Double = num1 / num2
``````

## Formatting Double Values

You can format a Double value to a specific number of decimal places using the ToString method. For example:

``````
Dim value As Double = 12.3456789

Console.WriteLine(value.ToString("F2")) ' Output: 12.35
Console.ToString("N3")) ' Output: 12.346
``````

## Conclusion

The Double data type in VB is an essential data type for handling decimal values that require high precision and a wide range. It allows you to perform various arithmetic operations and format the values as needed. Understanding and utilizing the Double data type effectively can greatly enhance your ability to work with complex mathematical calculations and other numeric operations.