numbers which are quite meaningless will be replaced by "X"... and numbers which form pattern/s will be replaced by "A", "B", "C"....

refer to samples below....

2999901 = XAAAAXX

2999902 = XAAAAXX

2999111 = XAAABBB

2999222 = XAAABBB or ABBBAAA

2991111 = XAABBBB

2993333 = XAABBBB

2993888 = XAAXBBB

2994888 = XAAXBBB

2999499 = XAAAXAA

2999599 = XAAAXAA

2999299 = XAAAXAA

2999288 = XAAAXBB or ABBBACC

2999399 = XAAAXAA

2999229 = ABBBAAB

2999292 = ABBBABA

2999889 = XAAABBA

2999494 = XAAABAB

2992999 = XAAXAAA

2999200 = XAAAXBB

2999199 = XAAAXAA

2997997 = XAABAAB

2999946 = XAAAAXX

2999947 = XAAAAXX

2999948 = XAAAAXX

2999954 = XAAAAXX

2999956 = XAAAAXX

2999983 = XAAAAXX

2999984 = XAAAAXX

2999985 = XAAAAXX

2999986 = XAAAAXX

2999987 = XAAAAXX

2999959 = XAAAAXA

2999969 = XAAAAXA

2999989 = XAAAAXA

2999900 = XAAAABB

2999911 = XAAAABB

2999922 = XAAAABB or ABBBBAA

2999933 = XAAAABB

2993000 = XAAXBBB

2994000 = XAAXBBB

2995000 = XAAXBBB

2996000 = XAAXBBB

2998000 = XAAXBBB

2995999 = XAAXAAA

2996999 = XAAXAAA

2997999 = XAAXAAA

2998999 = XAAXAAA

2993377 = XAABBCC

2993388 = XAABBCC

2993399 = XAABBAA

2998800 = XAABBCC

2992299 = XAABBAA

2997799 = XAABBAA

2998899 = XAABBAA

2992424 = XAABCBC

2998282 = XAABCBC

2997979 = XAABCBC

2998080 = XAABCBC

2993322 = XAABBCC

2995599 = XAABBAA

2998880 = XAABBBX

2998881 = XAABBBX

2998882 = XAABBBX

2998883 = XAABBBX

2998889 = XAABBBX

aside from the pattern shown...

another 1 is....

if at least three zeros or eights are consecutive, they shouldn't be replaced by the letters but the numbers "0" and "8" themselves...

e.g.

2999888 = XAAA888

2998888 = XAA8888 or XXX8888

2340000 = XXX0000

3155000 = XXXX000

2488888 = XX88888

8888459 = 8888XXX

1200001 = XX0000X

thank you very much!!!