Table: poland_voivodeship
Columns: abbreviation
voivodeship
capital
area_km_1998
population_1980
no_of_cities
no_of_communes

Question: What's the area of the voivodenship with 51 communes?
SQL: SELECT "area_km_1998" FROM poland_voivodeship WHERE "no_of_communes" = 51

Question: How big (in km2) is the voivodenship also known by the abbreviation KN?
SQL: SELECT "area_km_1998" FROM poland_voivodeship WHERE "abbreviation" = 'kn'

Question: How many people lived in the voivodenship whose capital is Siedlce in the year of 1980?
SQL: SELECT "population_1980" FROM poland_voivodeship WHERE "capital" = 'Siedlce'

Question: How many different voivodenship have 747 900 citizes?
SQL: SELECT COUNT("voivodeship") FROM poland_voivodeship WHERE "population_1980" = '747 900'