Given MECHANICS is coded as HCEMASCIN
- M $\leftrightarrow$ H (4)
- E $\leftrightarrow$ C (3)
- C $\leftrightarrow$ E (2)
- H $\leftrightarrow$ M (1)
- A $\leftrightarrow$ A (5)
- N $\leftrightarrow$ S (9)
- I $\leftrightarrow$ C (8)
- C $\leftrightarrow$ I (7)
- S $\leftrightarrow$ N (6)
The middle number position has not changed the rest of starting 4 words reverse and last 4 also reverse.
Hence, POSTER will be coded as
- P $\leftrightarrow$ S (3)
- O $\leftrightarrow$ O (2)
- S $\leftrightarrow$ P (1)
- T $\leftrightarrow$ R (6)
- E $\leftrightarrow$ E (5)
- R $\leftrightarrow$ T (4)
Hence, POSTER will be coded as SOPRET