Dictionary invalid token error

[brad]

This works:

 >>> area_group = {001:06, 002:04, 003:04, 006:9}

This does not (one the end, 09 is used instead of 9)

 >>> area_group = {001:06, 002:04, 003:04, 006:09}
   File "<stdin>", line 1
     area_group = {001:06, 002:04, 003:04, 006:09}
SyntaxError: invalid token

Why does 09 cause an invalid token while 9 does not?

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Python 2.4.4 (#2, Apr  5 2007, 18:43:10)
[GCC 4.1.2 20061115 (prerelease) (Debian AMD64 4.1.1-21)] on linux2