Let me implement my very limited knowledge of mathematics.
The format is T 999 XXX
Tuna possibility ya kuwa na namba 100 - 999. Sijawahi kuona T 099 XXX. I stand to be corrected.
Hivyo kimahesabu tuna namba tofauti 999 - 100 = 899
X stands for alphabetic characters except O and I -> 24 letters
Out of the 24 letters, 3 can be arranged in format XXX.
Kupata the total possible number of XXX arrangement ni 24*24*24
The result: 13,824 arrangements (from AAA to ZZZ)
Kwa kila namba kati ya 100-999 tuna combinations za herufi 13,824.
Kwahiyo total number of T 999 XXX combinations ni 899 * 13,824 = 12,427,776
Hivyo basi, mfumo huu wa usajili unaweza kuhandle jumla ya vyombo 12,427,776 (Milioni kumi na mbili laki nne ishirini na saba elfu mia saba sabini na sita).
Tangu mfumo huu uanze kutumika mnamo mwaka 2005 tumekwisha exhaust combinations through T 999 DZZ (Assumption). Tujaribu kuangalia ni vyombo vingapi vimekwisha sajiliwa.
Arrangements kati ya AAA - DZZ. Hi ni A(AA-ZZ) B(AA-ZZ) C(AA-ZZ) D(AA-ZZ).
Kila (AA-ZZ) combo ina possibilities 24*24 = 576
Hivyo kwa A mpaka D ni A(552) + B(552) + C(552) + D(552) = 4 * 576 = 2,304
Jumla ya vyombo = 899 * 2304 = 2,071,296
Hivyo nasi, kuanzia T 100 AAA mpaka T 999 DZZ vyombo 2,071,296 vimekwisha sajiliwa. Mind you kuna pikipiki na bajaji zilizokuwa zinakimbiza sana namba.
Hii ina maana kuanzia T 100 EAA mpaka mwisho wa mfumo, magari 10,356,480 yanaweza kusajiliwa.
Imetuchukua miaka 12 kusajili vyombo 2,071,296. Je, tukitoa pikipiki na bajaji, itatuchukua miaka mingapi kusajili vyombo 10,356,480?? Data zaidi zinatakiwa. Kama kuna mwenye gari DAA atuambie ilisajiliwa mwaka gani tujue ni muda gani umepita.
N.B Wataalamu wa hesabu tafadhalini sahihisheni logic yangu. Jibu hili sio definitive.