1. How many tiles with dimensions $15 \times 15$ cm are needed to tile a wall that is 3 m 6 dm long and 27 dm wide $?$
1. The first method of solving.
1) $15 \times 15=225$ (cm$^2$ - the area of one tile;
2) $360 \times 270=97200\left(\mathrm{~cm}^{2}\right)$ - the area of the walls;
3) $97200: 225=432$ (tiles).

The second method of solving (Rukhov Arseny, student of School No. 25).

1) $360: 15=24$ (tiles) - will fit in one row along the length of the wall;
2) $270: 15=18$ (tiles) - will fit in one row along the width of the wall;
3) $24 \times 18=432$ (tiles).

Answer: 432 tiles will be required.