2. Suppose there are several pixels in the horizontal direction (X pixels) and several pixels in the vertical direction (set to Y), then how many pixels are there in the whole picture (set to Z)? Is z = x × y.

3. Specifically, the photo has 4000 pixels in the horizontal direction (4000 dots in a row) and 3000 pixels in the vertical direction (3000 rows). Then the total number of pixels is 4000× 3000 = 1200000, which is12 million pixels, so it can be said that the resolution of this photo is12 million.