In Python, variables are used to store data values. One of the common data types used in Python programming is a double which is a floating-point number. This tutorial will teach you how to declare a double variable in Python and provide a few examples for better understanding.

### Step 1: Declare a double variable in Python

To declare a double variable in Python, you simply need to assign a floating-point number to a variable. This can be done using the following syntax:

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variable_name = float_value |

Where `variable_name`

is your desired variable name, and `float_value`

is the floating-point number. No additional keyword is needed to specify that the variable is a double, as Python automatically assigns the variable’s data type based on the given value.

For example:

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# Declaring a double variable height_in_meters = 1.75 # Printing the value and type of the variable print("Height in meters:", height_in_meters) print("Data type:", type(height_in_meters)) |

This will create a double variable called `height_in_meters`

with the value `1.75`

.

### Step 2: Using double variables in calculations

Double variables can be used seamlessly in arithmetic calculations and operations with other integers and float data types. Here’s an example using a double variable in a simple calculation:

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# Declare two double variables a = 5.0 b = 3.5 # Perform calculations addition = a + b multiplication = a * b # Print results print("Addition:", addition) print("Multiplication:", multiplication) |

This code creates two double variables, `a`

and `b`

, and performs addition and multiplication operations on them.

### Step 3: Formatting the output of double variables

When displaying the output of double variables, you might want to format the output to a specific number of decimal places. One way to achieve this is by using the `format()`

function.

Here’s an example:

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# Declare a double variable pi_value = 3.1415926535 # Format and print the output formatted_pi_value = format(pi_value, '.2f') # Format to 2 decimal places print("Pi value formatted to 2 decimal places:", formatted_pi_value) |

In this example, the `format()`

function is used to display the `pi_value`

with only two decimal places.

## Full Example Code

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# Declare a double variable height_in_meters = 1.75 # Printing the value and type of the variable print("Height in meters:", height_in_meters) print("Data type:", type(height_in_meters)) # Declare two double variables a = 5.0 b = 3.5 # Perform calculations addition = a + b multiplication = a * b # Print results print("Addition:", addition) print("Multiplication:", multiplication) # Declare a double variable pi_value = 3.1415926535 # Format and print the output formatted_pi_value = format(pi_value, '.2f') # Format to 2 decimal places print("Pi value formatted to 2 decimal places:", formatted_pi_value) |

## Output

Height in meters: 1.75 Data type: <class 'float'=""> Addition: 8.5 Multiplication: 17.5 Pi value formatted to 2 decimal places: 3.14

## Conclusion

Declaring a double variable in Python is quite simple and easy to use in various calculations or operations. In this tutorial, you learned how to declare, perform calculations, and format the output of double variables in Python.