30 is different, others are multiples of 4.

Second,

36= 1×36

36=2× 18

36=3× 12

36=4×9

36=6×6

There are five such rectangles (the last one is a square, because a square is also a rectangle).

Length and width are:

36 cm and 1 cm

18cm and 2cm

12cm and 3cm

9 cm and 4 cm

6 cm and 6 cm

3、

The number in hundreds is a multiple of 5, and it can only be 5.

The sum of three digits and rainstorm 6 is less than 10, which is a multiple of 3, so the sum of three digits must be divisible by 3. Between 6 and 10, only 9 satisfies the condition, and the hundredth digit is 5, so the sum of ten digits and single digits is 9-5=4.

The second and tenth digits are two consecutive odd numbers, 4= 1+3 = 3+ 1, so this three-digit number is 5 13 or 53 1.