The least number of square tiles required to pave the ceiling of a room 15m 17cm long and 9m 2cm broad is = ?

Answer: Option C

For the least number of tiles, the size of the tiles must be the maximum.
Maximum size of the tile = HCF of 1517 cm and 902 cm = 41 cm.
Hence, required number of tiles
$$\begin{array}{rl}& \text{ = }\frac{\text{Area of ceiling}}{\text{Area of each tile}}\\ & =\left(\frac{1517\times 902}{41\times 41}\right)\\ & =814\end{array}$$