Firstly, the numbers A and B are analyzed. If the zero in the unit of A is removed, it is the same as the counted number, then A is greater than B, A is a three-digit number, and B is a two-digit number. The hundred digits of A are the same as the ten digits of B, and they are all 4. The two digits of B are the ten digits of A, and the ten digits of B are the hundred digits of A, so A is: 420 and B is: 42.
2. There are five Sundays in September. If September 1 day is not Sunday, what day should it be!
September has 30 days, 30/7=4+2. Analysis: September has 4 whole weeks, 4 Sundays, and a certain September has 5 Sundays. If September 1 day is not a Sunday, then only Saturday can guarantee five Sundays in September.