Serbia is 38,737 times larger than Monaco.
Area: 2 km2 World Factbook
Population: 30,508 (July 2014) World Factbook
Monaco, officially the Principality of Monaco, is a sovereign city-state and microstate, located on the French Riviera in Western Europe. It is bordered by France on three sides; one side borders the Mediterranean Sea. Wikipedia
Area: 77,474 km2 World Factbook
Population: 7,209,764 (July 2014) World Factbook
Serbia, officially the Republic of Serbia, is a country located at the crossroads of Central and Southeast Europe, covering the southern part of the Pannonian Plain and the central Balkans. Wikipedia