How many {significant person} are for {power} ?
The number of significant people in power is?
How many significant people are there in power?
SELECT ( COUNT ( ?v ) AS ?n ) { resource:Power property:significant_person ?v }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q25107> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P3342> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

SELECT (COUNT(?obj) AS ?value ) { wd:Q25107 wdt:P3342 ?obj }
10