Mobile Scratch Cards similarities

[lockedside]

Dear friends,
I am in a temporal visit to Yeman ( an arabic country ). I bought an MTN sim card and started using the service, I bought two recharging cards serialized:
00070 309 508 1402
00070 309 508 1404

TO My shock I have seen that the numbers differ only by 6 places:
79 50 81 40 27 42 29
79 50 81 40 45 90 07

After all, I never supposed that a company might not think about using strong MD5 or SHA1 codes to estimate their scratch cards!! this would give out a probability to find new numbers by 1:1000000-2 ( my two scratch cards I bought!!)

I am wondering what kind of coding estimations this company uses? can I use my own estimations to find numbers?


Yours,
lockedside

[lockedside]

Dear friends, I have noticed a new hint in this post!! when I buyed another card today I found that the hidden numbers are actually composed literarly from the serial number of the card!!!! followed by 5 random numbers not 6 check this out!!:
serial : 000703095081402
hidden code: 7950840274229

Believe me, this is the case for all the cards!! which downs the probability to 1:100000-2!!!

Yours,
Lockedside