Today matematics are moving away from understanding basics & core methodology. Level of the difficulties are reducing. Questions are becoming more simpler. Hence I would like to see the difficulty level in years Ranging 1940-1970. These Question papers will help improve students to improve in understanding rather than making students to behave like CLERKS by solving repeatadle the similar typ questions not having intelligance in the Questions itself.
Here are some problems from the Stanford scholarship examination. I found them on the easier side, but that may be because they are quite old. I feel competitive mathematics has become significantly harder in the past, say, 20 years, but that is just a personal opinion.