Remark
So CAB is a base 16 number? I hope that's correct. I'll treat it that way. If I am incorrect, please leave a note and I'll modify my answer accordingly.
Expand
A = 10 in decimal
B = 11 in decimal
C = 12 in decimal
B is the "units" value in decimal it is 11
A is the "tens" value or 12 place and in decimal you would get 12 * 10 = 120
C is the "hundreds" value or 12^2 place and in decimal you would get 144*12 =1728
Now you need to all all three results together. 11 + 120 + 1728 = 1850
Answer
(CAB)_16 = 1850 in decimal
