How to use reg add to write hexadecimal REG_DWORDs

I can't find any documentation on the internet for how to do this, and since I just discovered it, I thought I'd give something back.

If you want to have reg.exe write hexadecimal values into the registry, you can do so like this:

reg.exe add "key" /v "value" /t REG_DWORD /v 0x555

For decimal, just pass the number like usual; that's the default format.