The "Freeola Customer Forum" forum, which includes Retro Game Reviews, has been archived and is now read-only. You cannot post here or create a new thread or review on this forum.
If you can't find it there, Google is usually pretty good if you just type in "Name of Game" + format + "walkthrough" then sift through the results a bit.
(21+500=521, 521+500=1021 etc.)
The walkthrough is here if you want to use it.
1123581321
or
1231853211
I'm guessing the XBox version uses the same sequence.