Turn the NumLock key on. That should do it.
The shift+Opt notations are for Mac.
and edit.....
UhOh, are you using a laptop or a desktop? A laptop usually had the number keys in the letter keys of the keyboard so when you turn on the NumLock (hit that key) the function of the keys designated change to Numbers. That means you have to turn NumLock on, key in the ASCII code, then turn NumLock off before you can proceed.
If a desktop, the keys would, in most cases, be to the right of the letter keys.