Converting a binary number to a decimal number in Python can be accomplished using several methods. Below are some commonly used approaches:
###### 1. Using the Built-in *int()* Function

Python's *int()* function can directly convert a binary number (represented as a string) to its decimal equivalent by specifying the base. Here’s how it works:
binary_number = '1101' # Binary representation
decimal_number = int(binary_number, 2) # Converting to decimal
print(decimal_number) # Output: 13

In this example, *'1101'* is treated as a binary number, and specifying *2* as the second argument tells Python to convert it from base 2 to base 10.
###### 2. Using Mathematical Approach

You can manually convert a binary number to decimal by multiplying each bit by its corresponding power of 2. This can be implemented using a loop or a list comprehension. Here’s how you can do it:
binary_number = '1101' # Binary representation
decimal_number = sum(int(bit) * (2 ** idx) for idx, bit in enumerate(reversed(binary_number)))
print(decimal_number) # Output: 13

In this method, each bit is accessed, starting from the least significant bit (rightmost), and is multiplied by *2* raised to the power of its position.
###### 3. Using the *bin()* Function for Verification

Python provides the *bin()* function to convert a decimal number back to binary. This can be handy for verifying the conversion. Here is how it works:
decimal_number = 13
binary_representation = bin(decimal_number) # Converts to binary
print(binary_representation) # Output: 0b1101

The *0b* prefix indicates that this representation is in binary.
###### Conclusion

Converting binary numbers to decimal in Python is straightforward, thanks to the built-in *int()* function. For educational purposes, understanding the mathematical approach can deepen comprehension of how number systems work. Both methods provide a reliable way to perform binary to decimal conversions, suitable for various applications in programming.