CREATE TABLE table_20937 ("Number" FLOAT, "Name" TEXT, "Kilometer" FLOAT, "Pavement" TEXT, "Length  ( m ) " FLOAT, "Average climb  ( % ) " FLOAT)

How many had a length of 455?
SELECT COUNT("Name") FROM table_20937 WHERE "Length (m)" = '455'
SELECT COUNT("Name") FROM "table_20937" WHERE "Length (m)" = '455'