http://puzzle4u.com/digit_game.html
Level 1
GY3C
Level 2
1DXX
Level 3
F92D
Level 4
VMM2
Level 5
1H8S
Level 6
45R9
Level 7
5LCV
Level 8
67VA
Level 9
BT5T
Level 10
ALS8
Level 11
FFGX
Level 12
Z6R8
Level 13
9NBP
Level 14
YY92
Level 15
KE5E
Level 16
74P8
Level 17
WE21
Level 18
T411
Level 19
FGFC
Level 20
MLP4
Level 21
UM33
Level 22
BI2V
Level 23
DDJL
Level 24
835N
Level 25
YVR9
Level 26
WQ8I
Level 27
QT2B
Level 28
KDDN
Level 29
JJ7H
Level 30
WYVC
Level 31
NEFH
Level 32
5RDZ
Level 33
L4HE
Level 34
1S2L
Level 35
J6CS