I did a small calculation a few days ago, and here is what I found:
Initial plan of MRVC was for 101 9 coach rakes. Each 9 coach rake consists of 3 units. These originally planned rakes have been allotted numbers in 2xxx series. Hence, in 2xxx series the last number will be 303 (101 multiplied by 3) (2303A, 2303 B, 2303 C).
Quantity of 9 car rakes added later by Railway board is 73. These added rakes have been allotted numbers in 1xxx series. So, by the same principle applied for 2xxx series, the last number in 1xxx series will be 219 (1219 A, 1219 B, 1219 C).
The exact number of rakes comes out to be 129 twelve coach rakes and 2 nine coach rakes. In 1xxx series, 54 twelve coach rakes and 3 units which can form 1 nine coach rake will be manufactured. Similarly in 2xxx series, 75 twelve coach rakes and 3 more units will be manufactured.
It is totally upto the authorities to decide whether the 2 nine coach rakes will be manufactured as complete rakes or loose coaches to be used as spares.