In a certain code language, ‘ POEM’ is written as ‘1351516’, ‘ROB’ is written as ‘21518’. What is the code for ‘MAID’ in that code language?

49113

1   2    3    4   5    6   7     8    9  10  11  12  13

 A   B   C    D   E    F   G    H    I    J    K    L   M

 ↓    ↓    ↓    ↓    ↓     ↓   ↓    ↓     ↓   ↓    ↓    ↓    ↓

 Z   Y    X   W   V    U   T    S    R   Q   P    O   N

26  25  24  23  22  21  20  19  18  17  16  15  14

***********************************************

THE LOGIC FOLLOWED HERE IS:

REVERSE THE APLHABET AND INDICATE WITH PLACE VALUE

POEM = MEOP.

M → PLACE VALUE → 13

E → PLACE VALUE → 5

O → PLACE VALUE → 15

P → PLACE VALUE → 16

AND,

ROB = BOR

B → PLACE VALUE → 2

O → PLACE VALUE → 15

R → PLACE VALUE → 18

SIMILARLY

MAID = DIAM

D → PLACE VALUE → 4

I → PLACE VALUE → 9

A → PLACE VALUE → 1

M → PLACE VALUE → 13