How do I generate a seven digit random number which is itself divisible by seven

Question

I am working on a program, and all of the parts work perfectly except one, that part is supposed to generate a seven digit random number which is divisible by 7.

I am aware that there are similiar questions to mine, but I did not find my anwser within them, and despite trying I was myself only capable of somethimes generating such a number.

Any idea how to do so?

Answer 1

You can use the modulo function (see set /?):

@echo off
setlocal

set "number=%random%%random%%random%%random%%random%%random%%random%"
set "number=%number:~0,7%"
set /a remainder=number %% 7
if %remainder% equ 0 (
  echo %number% is a multiple of 7
) else (
  echo %number% divided by 7 gives a rest of %remainder%
)

Just in case, leading zero(s) is/are ok or even desired as a possibility:

@echo off
setlocal

set "number=%random%%random%%random%%random%%random%%random%%random%"
set "number=%number:~-7%"
set /a remainder=7%number% %% 7
if %remainder% equ 0 (
  echo %number% is a multiple of 7
) else (
  echo %number% divided by 7 gives a rest of %remainder%
)