# Returns the N-th digit of a number counting from the right.
#
# Examples:
# get_nth_digit_from_right(12345, 1) # => 5
# get_nth_digit_from_right(12345, 2) # => 4
# get_nth_digit_from_right(12345, 3) # => 3
#
# @param input_number [Integer]
# The number to inspect.
#
# @param digit_position [Integer]
# The digit position (1-based, from the right).
#
# @return [Integer]
# The digit at the specified position.
#
# @raise [ArgumentError]
# If digit_position is less than 1.
def get_nth_digit_from_right(input_number, digit_position)
raise ArgumentError, "Digit position must be greater than 0." if digit_position < 1
# Handle negative numbers.
absolute_number = input_number.abs
# Calculate 10^(digit_position - 1) using integer arithmetic.
divisor = 1
(digit_position - 1).times do
divisor *= 10
end
# Shift the desired digit to the ones place.
shifted_number = absolute_number / divisor
# Extract the digit.
shifted_number % 10
end
# Program entry point.
def main
input_number = 12_745
first_digit = get_nth_digit_from_right(input_number, 1)
third_digit = get_nth_digit_from_right(input_number, 3)
fifth_digit = get_nth_digit_from_right(input_number, 5)
puts "Number: #{input_number}"
puts "1st digit from right: #{first_digit}"
puts "3rd digit from right: #{third_digit}"
puts "5th digit from right: #{fifth_digit}"
end
main
# run:
#
# Number: 12745
# 1st digit from right: 5
# 3rd digit from right: 7
# 5th digit from right: 1
#
