using System;
namespace DigitExample
{
internal static class Program
{
/// <summary>
/// Returns the N-th digit of a number counting from the right.
///
/// Examples:
/// GetDigit(12945, 1) => 5
/// GetDigit(12945, 2) => 4
/// GetDigit(12945, 3) => 9
/// </summary>
/// <param name="number">
/// The input number.
/// </param>
/// <param name="position">
/// The digit position (1-based, from the right).
/// </param>
/// <returns>
/// The digit at the specified position.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// Thrown when position is less than 1.
/// </exception>
private static int GetDigit(long number, int position)
{
if (position < 1) {
throw new ArgumentOutOfRangeException(
nameof(position),
"Position must be greater than 0.");
}
// Handle negative numbers.
number = Math.Abs(number);
// Calculate 10^(position - 1) using integer arithmetic.
long divisor = 1;
for (int i = 1; i < position; i++) {
divisor *= 10;
}
// Shift the desired digit to the ones place
// and extract it.
return (int)((number / divisor) % 10);
}
private static void Main()
{
long number = 12945;
Console.WriteLine($"Number: {number}");
Console.WriteLine($"1st digit from right: {GetDigit(number, 1)}");
Console.WriteLine($"3rd digit from right: {GetDigit(number, 3)}");
Console.WriteLine($"5th digit from right: {GetDigit(number, 5)}");
}
}
}
/*
run:
Number: 12945
1st digit from right: 5
3rd digit from right: 9
5th digit from right: 1
*/
