Eight to ten crabs per catty are called one or two crabs, that is, there are 8- 10 crabs per catty;

A catty of five to seven crabs is called one and a half crabs, that is, a catty 1 has 5-7 crabs;

Four to five crabs per catty are called two or two crabs, that is, 1 catty has 4-5 crabs;

Three or four crabs in a catty are called two and a half crabs, which means three or four crabs in a catty.

A catty is called three or two crabs, and a catty is called half a catty of crabs, both of which are born in two years; The crabs in 62, 72, 82 and 92 are all three-year-old crabs.