A solid concrete block weighs 150. N and is resting on the ground. The dimensions are 0.400 m, 0.200 m and 0.100 m. A number of similar blocks are then stacked on top of this one. Find out the smallest number of whole blocks (comprising the one on the ground) which can be stacked so that their weight makes a gauge pressure of at least two atmospheres on the ground below the first block?