[Georgio]

Код:

@echo off

set "$file=list.txt"
set $n=50

for /f "tokens=1* delims=:" %%i in ('findstr /n "^" "%$file%"') do set $j=%%j& call :sub %%i
exit

:sub
 set /a $m=(%~1-1)/%$n%+1
 set $m=0%$m%
 for %%i in ("%$file%") do (
  if not "%$i%"=="%$m:~-2%" (
   type nul>"%%~ni%$m:~-2%%%~xi"
   )
  (
  set /p="%$j%"<nul
  echo.
  )>>"%%~ni%$m:~-2%%%~xi"
  )
  set $i=%$m:~-2%
  exit /b