Fairly common types of problems


8 (AIME 1996) A bored student walks down a hall that contains a row of closed lockers, numbered 1 to 1024. He opens the locker numbered 1, and then alternates between skipping and opening each closed locker thereafter. When he reaches the end of the hall, the student turns around and starts back. He opens the first closed locker he encounters, then alternates between skipping and opening each closed locker thereafter. The student continues wandering back and forth in this manner until every locker is open. What is the number of the last locker he opens?


9 (AIME 1994) The function 18#18 has the property that, for each real number 13#13,

36#36

If 37#37, what is the remainder when 38#38 is divided by 1000?


10 (AIME 1993) Let 39#39 For integers 4#4, define 40#40. What is the coefficient of 13#13 in 41#41?


11 (AIME 1992) For any sequence of real numbers 42#42, define 43#43 to be the sequence 44#44, whose 21#21th term is 45#45. Suppose that all of the terms of the sequence 46#46 are 1 and that 47#47. Find 48#48.


12 (British Math Olympiad, 1977, #1) A non-negative integer 49#49 is assigned to each positive integer 21#21 in such a way that the following conditions are satisfied:

(a) 50#50, for all positive integers 51#51, and 21#21 ;
(b) 52#52 whenever the units digit of 21#21 (in base 10) is a `3'; and
(c) 53#53.
Prove that 52#52, for all positive integers 21#21.


13 (Putnam, 1999, problem A-1) Find polynomials 12#12, 54#54, and 55#55, if they exist, such that, for all 13#13:

56#56

See Polya Contest 1995 Power Round on attached sheet.