Lizzy: A four-layer pyramid is being built with each layer having three times as many sandstone blocks as the layer above it. The top layer is a single block. How many sandstone blocks are in the pyramid?.
Me: Hmmm, let me think. I think this is the detailed solution:
There are 1 * 3 = 3 blocks in the second layer. There are 3 * 3 = 9 blocks in the third layer. There are 9 * 3 = 27 blocks in the fourth layer. Thus, there are 1 + 3 + 9 + 27 = 40 sandstone blocks in the pyramid. Final answer: 40.