what is the {point in time} for {Saint Petersburg} has {population} as {2.92e+06} ?
When was the population of Saint Petersburg 2.92e+06?
When Saint Petersburg has its population 2.92e+06?
SELECT ?u WHERE { FILTER ( ?k = 2.92e+06 ) . resource:Saint_Petersburg property:population ?t . ?t property:point_in_time ?u . ?t property:population ?k }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q656> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1082> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <2.92e+06> .
?statement <http://www.wikidata.org/entity/P585> ?value. 
} 

SELECT ?value WHERE { wd:Q656 p:P1082 ?s . ?s ps:P1082 ?x filter(contains(?x , '2.92e+06')) . ?s pq:P585 ?value}