Create n files with random number value in loop batch

how can I generate n files which includes random number using batch? I have:

@echo off
set /p howManyFiles=How many files to generate: 
FOR /L %%i IN (1, 1, %howManyFiles%) DO (
    set /a num=%random% %%100 +1
    echo !num! >"C:\xxx\file.txt"
)
pause

but it generates only 1 file.