The diameter of a six-inch cake is about15cm, which is suitable for one or two people. If the number of people is two to four, you can consider choosing an 8-inch cake. It is more suitable for such people to eat an 8-inch cake, because the diameter of an 8-inch cake is about 20 cm, which can meet the needs of most people.

When choosing the size of the cake, besides the number of people, one should also consider one's taste and food intake. Some people may like to eat smaller cakes, while others may like to eat bigger cakes. In addition, for people who especially like sweets, it may be more appropriate to choose a slightly larger cake.

In short, when choosing the size of the cake, we need to comprehensively consider the number of people, taste and food intake. If you choose it improperly, it may lead to waste or insufficient food. Therefore, it is recommended to consult the clerk before buying the cake or make a suitable choice according to personal circumstances.