Decathlon

The men’s decathlon consists of ten events that are held on two consecutive days. The first day’s events include, in order, a 100-meter run, the long jump, shot put, high jump and a 400-meter run. The second day’s events, in order, include the 110-meter hurdles followed by the discus throw, pole vault, javelin throw and a 1500-meter run. The competition
In the 2004 Games, 39 men participated in the Olympic decathlon. Decathlon rules
The rules for each event within the decathlon are generally the same as for the individual events themselves, with a few exceptions. Most notably, runners are allowed two false starts instead of one, while competitors receive only three attempts in throwing and jumping events. Competitors cannot pass on any event. Failing to attempt any single event results in disqualification.

Points are awarded to each athlete according to his time or distance, not his placement in the field, according to pre-set formulas. Those formulas have been revised frequently over the years, making head-to-head comparisons of many decathlon performances difficult. See the IAAF Scoring Tables for explanations and comparisons of the formulas employed over the past century.
If there is a tie in points after 10 events, the victory goes to the competitor who out-scored his rival in more events. If that tiebreaker results in a draw, the victory goes to the decathlete who scored the most points in any single event