The fifth International Combinatorics Olympiad (ICO 2025) was held in Tehran on October 30-31, attracting around 5,000 participants from over 70 countries. This unique competition focused on combinatorics, featuring online scoring and ranking to engage students of all educational levels. Participants faced a series of challenges, including 15 short-answer questions on Day 1 and seven long-answer questions on Day 2. Concurrently, the 12th Iranian Geometry Olympiad drew 10,000 students from 50 countries. Iranian students also excelled in various international competitions, earning multiple medals in disciplines like artificial intelligence, economics, biology, physics, and mathematics, showcasing their mathematical talent on a global platform.