How to get the first N digits of a BigInteger in Python

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# Extracts the first n digits from a large integer.
# Python's built-in int type already supports arbitrarily large values,
# so converting the number to a string is the most direct and efficient way
# to access its digits.
def first_n_digits(value: int, n: int) -> str:
    # Convert the integer to its decimal string representation.
    s = str(value)

    # If n exceeds the number of digits, return the whole number.
    if n >= len(s):
        return s

    # Return the first n characters (digits).
    return s[:n]


def main():
    # Define a very large integer directly.
    # Python handles large integers seamlessly.
    big_number = 9876543210987654321098765432109876543210

    # Choose how many digits to extract.
    n = 18

    # Extract the first n digits.
    result = first_n_digits(big_number, n)

    # Display the result.
    print(f"First {n} digits:", result)


if __name__ == "__main__":
    main()



"""
run:

First 18 digits: 987654321098765432

"""

 



answered Aug 14 by avibootz
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