12. Mario writes the positive integers in a grid with 7 columns, as shown in the figure. Since he dislikes the number 11, all multiples of 11 are missing from his list. We denote the cell that is in the $m$-th row (counting from the top) and the $n$-th column (counting from the left) as $(m ; n)$: for example, the cell $(2 ; 4)$

| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| :---: | :---: | :---: | :---: | :---: | :---: | :---: |
| 8 | 9 | 10 | 12 | 13 | 14 | 15 |
| 16 | 17 | 18 | 19 | 20 | 21 | 23 |
| 24 | 25 | $\cdots$ | $\cdots$ | $\cdots$ | $\cdots$ | $\cdots$ |

contains the number 12. In which cell will the number 1500 be located?
(A) $(195 ; 6)$
(B) $(215 ; 2$
(C) $(214 ; 2)$
(D) $(194 ; 3)$
(E) $(193 ; 6)$
(12) The correct answer is $(A)$.

The multiples of 11 between 1 and 1500 are 136, since $1000=136 \cdot 11+4$. By eliminating these numbers, a list of 1364 numbers remains to be placed in the table, with the number 1500 being the last: since $1364=194 \cdot 7+6$, this last number will therefore fall in the $6^{th}$ column of the $195^{th}$ row.

Question proposed by Carmelo Di Stefano.