Question: What is the 1880 figure when 1860 is N/A and 1910 is 494?
SQL: SELECT "1880" FROM "2-18081953-1" WHERE "1860" = 'N/A' AND "1910" = 494.0;

Question: What is the 1920 number when 1890 is greater than 1236, 1910 is less than 1177 and the city is vacaville?
SQL: SELECT SUM("1920") FROM "2-18081953-1" WHERE "1890" > 1236.0 AND "City" = 'vacaville' AND "1910" < 1177.0;