Question

The least number of square tiles required to pave the ceiling of a room 525 centimetre long and 378 centimetre broad is:

• A. 178
• B. 150
• C. 380
• D. 450

Answer 1

Answer:

D. 450

To find the least number of square tiles, use the largest possible square tile size.

Side of the largest square tile:

$\gcd(525,378)=21$

So, each square tile has side (21) cm.

Number of tiles needed:

$\frac{525}{21}\times\frac{378}{21}$

$25 \times 18 = 450$
Least number of square tiles required = 450