Use HCF to find out the minimum number of tiles needed:
63 = 3 x 3 x 7
28 = 2 x 2 x 7
When constructing the square, the sides will be made up of 28 and 63, which are the above components,
So we need to find out the highest common factor to know the least number for 1 side of the square:
Upon broken down,
We can figure out "the length of the square" by constructing from the above pieces (HCF):
2 x 2 x 3 x 3 x 7 = 252cm

Hence the square will be 252cm in length
Total area of square:
252 x 252 = 63504cm^2
Area of 1 tile:
28 x 63 = 504cm^2
:. Minimum Number of tiles needed = 63504 / 504
= 126 //

B)
5 = 5
6 = 3 x 2
8 = 2 x 2 x 2
LCM of the 3 numbers are
5 x 3 x 2 x 2 x 2 = 120
Since number is between 400 to 500,
And it's a multiple of 120,
The only solution is 480 tiles //