How many bricks 9.5 cm wide x 20 cm long are required to cover a patio 4 meters wide by 5 meters long?

So you need to know the area of patio in cm, so you need to caculate area and than convert. 

4 x 5 = 20 m
20 m = 200000 cm

once you know area, you need to know the area of bricks.

9.5 x 20 = 190

Than divide patio area by brick area
200000 divide 190 = 1052 .63

since there cant be 1052.63 bricks, just round up to 1053.

so 1053 bricks are required for this patio.

Hope this helped!