According TS24.301 of 9.9.3.12 sub-section.
The format of MCC and MNC.
In detailed, the PLMN identity is combination of MCC and MNC. It is 3bytes and it is arranged as:
MCC digit 2 + MCC digit 1 ------> 1 byte
MNC digit 3 + MCC digit 3 ------> 2 byte
MNC digit 2 + MNC digit 1 ------> 3 byte
For ex:
PLMN identity: 130182
13 ---> 1 byte
01 ---> 2 byte
82 ---> 3 byte
MCC = [MCC digit 1][MCC digit 2][MCC digit 3] ---> 311
MNC = [MNC digit 1][MNC digit 2][MNC digit 3] ---> 280
