# File lib/spreadsheet/excel/writer/worksheet.rb, line 669
  def write_number row, idx
    # Offset Size Contents
    # 0 2 Index to row
    # 2 2 Index to column
    # 4 2 Index to XF record (➜ 6.115)
    # 6 8 IEEE 754 floating-point value (64-bit double precision)
    value = row[idx]
    case value
    when Date, Time
      value = encode_date(value)
    end
    write_cell :number, row, idx, value
  end