Thru 2003 there were 44 IMOs, each with 6 problems, except for 1960 and 1962 which each had 7, giving a total 266 problems in all.
The IMO got noticeably harder in the late 1980s. There are two separate papers of 3 problems each. The idea is that in each paper the problems are in order of increasing difficulty. That is not always true. But in the last 10 years the last problem in the second paper has usually been hard.
Many thanks to all those who supplied solutions where I failed, or pointed out errors, or supplied better solutions. There are still some solutions which are clumsy or inelegant, and maybe even some which are wrong (although I am not aware of any). All suggestions for improvement would be most welcome. [email: hoahkh at gmail dot com]
There are some technical notes on formats etc below.
1st International Mathematical Olympiad 1959
2nd International Mathematical Olympiad 1960
3rd International Mathematical Olympiad 1961
4th International Mathematical Olympiad 1962
5th International Mathematical Olympiad 1963
6th International Mathematical Olympiad 1964
7th International Mathematical Olympiad 1965
8th International Mathematical Olympiad 1966
9th International Mathematical Olympiad 1967
10th International Mathematical Olympiad 1968
11th International Mathematical Olympiad 1969
12th International Mathematical Olympiad 1970
13th International Mathematical Olympiad 1971
14th International Mathematical Olympiad 1972
15th International Mathematical Olympiad 1973
16th International Mathematical Olympiad 1974
17th International Mathematical Olympiad 1975
18th International Mathematical Olympiad 1976
19th International Mathematical Olympiad 1977
20th International Mathematical Olympiad 1978
21st International Mathematical Olympiad 1979
22nd International Mathematical Olympiad 1981
23rd International Mathematical Olympiad 1982
24th International Mathematical Olympiad 1983
25th International Mathematical Olympiad 1984
26th International Mathematical Olympiad 1985
27th International Mathematical Olympiad 1986
28th International Mathematical Olympiad 1987
29th International Mathematical Olympiad 1988
30th International Mathematical Olympiad 1989
31st International Mathematical Olympiad 1990
32nd International Mathematical Olympiad 1991
33rd International Mathematical Olympiad 1992
34th International Mathematical Olympiad 1993
35th International Mathematical Olympiad 1994
36th International Mathematical Olympiad 1995
37th International Mathematical Olympiad 1996
38th International Mathematical Olympiad 1997
39th International Mathematical Olympiad 1998
40th International Mathematical Olympiad 1999
41st International Mathematical Olympiad 2000
42nd International Mathematical Olympiad 2001
43rd International Mathematical Olympiad 2002
44th International Mathematical Olympiad 2003
