Python:

python
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num = float(input("Enter a number: "))

# Calculate the square
square = num ** 2

# Display the result
print("The square of", num, "is", square)
Explanation (Python):

The program starts by prompting the user to enter a number using the input function and stores the entered value in the num variable, which is converted to a float using the float function.
The square of the number is calculated using the exponentiation operator ** and stored in the square variable.
Finally, the result is displayed using the print function, which concatenates the strings and variables by separating them with commas.
All three solutions prompt the user for a number, calculate the square of that number, and display the result. The code is written in a language-specific syntax and follows a similar logic for user input, calculation, and output.