Question: How many scientists are known for the Manhatten Project?
SPARQL:
SELECT DISTINCT COUNT(?uri) WHERE {?uri <http://dbpedia.org/property/knownFor> <http://dbpedia.org/resource/Manhattan_Project>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Scientist>}