CREATE TABLE table_71726 ("Number" FLOAT, "Name" TEXT, "Builder" TEXT, "Type" TEXT, "Works number" FLOAT, "Date" FLOAT)

What number has the builder ruston hornsby, the date 1961, and the name Topsy?
SELECT COUNT("Number") FROM table_71726 WHERE "Builder" = 'ruston hornsby' AND "Date" = '1961' AND "Name" = 'topsy'
SELECT COUNT("Number") FROM "table_71726" WHERE "Builder" = 'ruston hornsby' AND "Date" = '1961' AND "Name" = 'topsy'