find the number of square tiles each of side of 50cm which will be required to cover the floor of a room which is 4m long and 3m wide.

Each side of square tile = 0.50 m
Area of each tile = ${\left(0.50\right)}^2 {\mathrm{m}}^2 = 0.25 {\mathrm{m}}^2$
Length of floor = 4 m
Width of floor = 3 m
So, Area of floor = $\left(4\times 3\right) {\mathrm{m}}^2 = 12 {\mathrm{m}}^2$
Therefore, Number of square tiles required = $\frac{\mathrm{Area} \mathrm{of} floor}{\mathrm{Area} \mathrm{of} \mathrm{each} \mathrm{square} tile}= \frac{12}{0.25} = 48$