There are several sets of this question. First of all, the length of 30 cm is twice the length and width of a cuboid, so 30 is divided by 2 to get 15, plus a number of1+14; 2+ 13; 3+ 12; 4+ 1 1; 5+ 10; 6+5; 7+8, the largest area is the smallest difference between the two numbers, that is, if there are several groups, it is a large group, so the largest is 7 times 8, and you get 56. The smallest is the maximum difference between two numbers, that is, 1 times 14, which is equal to 14.