Convert excel columns to integers

excel_column_index_converter.rb

CHAR_TO_INDEX = ('A'..'Z').to_enum.with_index.to_h.transform_values {|v| v+1}

def getNumber(column)
  total_indices = CHAR_TO_INDEX.size
  chars_array = column.chars
  last_char = chars_array.pop
  result = 0
  
  chars_array.each_with_index do |char, index|
    result += total_indices * CHAR_TO_INDEX[char] * (index + 1)
  end
  
  result += CHAR_TO_INDEX[column.chars[-1]]
end

puts getNumber('ZA')
puts getNumber('ZZ')
puts getNumber('A')
puts getNumber('Z')
puts getNumber('AA')