RMO or Regional Math Olympiad is the first round of mathematics contest (in India) leading to the prestigious International Mathematics Olympiad. It is held in the month of December (first Sunday of December).
The test is conducted in each of the 19 regions of India. From each region about 30 students are selected for the next level (Indian National Math Olympiad). This next level (INMO) is held in February. About 600 students appear in this INMO. Among these 600 students 35 are selected for a one month long camp (International Math Olympiad Training Camp) held in summer in Mumbai. From this training camp a team of 6 students are sent to the most prestigious mathematics contest on earth: International Math Olympiad. Champions in IMO are held in high esteem through out the world and accepted by leading universities like Harvard, Princeton etc.