1. There is a game called "2 1 point" in poker games. The rules of the game are: take any four cards (except big and small kings) and put these four numbers (A= 1, J= 1 1, Q= 12, K = 60). If the result 24 becomes 1, 2, 3, 4, … in turn, the following operations can be performed:

(2- 1)×(4-3)= 1; (2 + 1)-(4-3)= 2; (2 + 1)×(4-3)= 3; (2 + 1)+ (4-3)= 4;

Q: (1) How far can the above operations be calculated continuously?

(2) If the operation is not limited to addition, subtraction, multiplication and division, what is the conclusion?

[Answer: (1) can be counted as 28; (2) It can be counted as 33)]

There are several numbers. The first number is a 1, the second number is a2, and the third number is A3.

The nth number is one. If a 1=-0.5, starting from the second number, each number is equal to 1 and the number before it.

The reciprocal of the difference.

(1) Calculate A2 = _ _ _ _ _ _

a3=________

a4=_________

(2) Guess A1998 = _ _ _ _ _ _ _

a 2000 = _ _ _ _ _ _ _ _ _ _ _ _ _ _