How many famous five books are there?

They are;

1.Five on a Treasure Island (1942)

2.Five Go Adventuring Again (1943)

3.Five Run Away Together (1944)

4.Five Go to Smuggler's Top (1945)

5.Five Go Off in a Caravan (1946)

6.Five on Kirrin Island Again (1947)

7.Five Go Off to Camp (1948)

8.Five Get Into Trouble (1949)

9.Five Fall Into Adventure (1950)

10.Five on a Hike Together (1951)

11.Five Have a Wonderful Time (1952)

12.Five Go Down To The Sea (1953)

13.Five Go To Mystery Moor (1954)

14.Five Have Plenty Of Fun (1955)

15.Five on a Secret Trail (1956)

16.Five Go to Billycock Hill (1957)

17.Five Get Into a Fix (1958)

18.Five on Finniston Farm (1959)

19.Five Go to Demon's Rocks (1960)

20.Five Have a Mystery To Solve (1961)

21.Five Are Together Again (1962