So we have cylinder with area 1.2*0.5=0.6

We want to cover it 2 times so 0.6*2=1.2

If 0.5 is side of square (rectangle actually) the radius is 0.25. We have to calculate area of base and top too, so

1.2+0.785=1.985 - total area
Now we just have to divide 1.985 by 0.56 to see how many cans he does he need.
1.985:0.56=3.54====> 4 because he cant buy 3.54 of it.
The result is 4.