Question: How many naval guns did these battleships carry, in which the Japanese aircraft carrier Shinano was the third of these battleships?

Context paragraphs:
Iowa-class battleship: The "Iowa"-class battleships were a class of six fast battleships ordered by the United States Navy in 1939 and 1940 to escort the Fast Carrier Task Forces that would operate in the Pacific Theater of World War II.  Four were completed, two more were laid down but canceled in August 1945, at war's end, and both hulls were scrapped in 1958.  Like other third-generation American battleships, the "Iowa"s followed the design pattern set forth in the preceding "North Carolina"-class and "South Dakota"-class battleships, which emphasized speed in addition to secondary and anti-aircraft batteries.  Based on wartime experience, they were to serve as fast escorts for "Essex"-class aircraft carrier s.

Battle of Taranto: The Battle of Taranto took place on the night of 11–12 November 1940 during the Second World War between British naval forces, under Admiral Andrew Cunningham, and Italian naval forces, under Admiral Inigo Campioni.  The Royal Navy launched the first all-aircraft ship-to-ship naval attack in history, employing a small number of obsolescent Fairey Swordfish biplane torpedo bombers from the aircraft carrier  in the Mediterranean Sea.  The attack struck the battle fleet of the "Regia Marina" at anchor in the harbour of Taranto using aerial torpedoes despite the shallowness of the water.  The devastation wrought by the British carrier-launched aircraft on the large Italian warships was the beginning of the ascendancy of naval aviation over the big guns of battleships.  According to Admiral Cunningham, "Taranto, and the night of November 11–12, 1940, should be remembered for ever as having shown once and for all that in the Fleet Air Arm the Navy has its most devastating weapon."

Japanese aircraft carrier Shōhō: Shōhō (Japanese: 祥鳳, "Auspicious Phoenix" or "Happy Phoenix") was a light aircraft carrier of the Imperial Japanese Navy.  Originally built as the submarine support ship "Tsurugizaki" in the late 1930s, she was converted before the Pacific War into an aircraft carrier and renamed.  Completed in early 1942, the ship supported the invasion forces in Operation MO, the invasion of Port Moresby, New Guinea, and was sunk by American carrier aircraft on her first combat operation during the Battle of the Coral Sea on 7 May.  "Shōhō" was the first Japanese aircraft carrier to be sunk during World War II.

Japanese aircraft carrier Shinano: Shinano (信濃 ) , was an aircraft carrier built by the Imperial Japanese Navy (IJN) during World War II, the largest such built up to that time.  Laid down in May 1940 as the third of the "Yamato"-class battleship s, "Shinano"' s partially complete hull was ordered to be converted to a carrier following Japan's disastrous loss of four fleet carriers at the Battle of Midway in mid-1942.

Joseph F. Enright: Joseph Francis Enright (September 18, 1910, Minot, North Dakota – July 20, 2000, Fairfax, Virginia) was a submarine captain in the United States Navy.  He is best known as the man who sank the Japanese aircraft carrier "Shinano"–the "most significant single submarine sinking of World War II."

Yamato-class battleship: The "Yamato"-class battleships (大和型戦艦 , Yamato-gata senkan ) were battleships of the Imperial Japanese Navy (IJN) constructed and operated during World War II.  Displacing 72000 LT at full load, the vessels were the heaviest battleships ever constructed.  The class carried the largest naval artillery ever fitted to a warship, nine 460-millimetre (18.1 in) naval guns, each capable of firing 1460 kg shells over 42 km .  Two battleships of the class ("Yamato" and "Musashi" ) were completed, while a third ("Shinano" ) was converted to an aircraft carrier during construction.

Japanese aircraft carrier Akagi: Akagi (Japanese: 赤城 "Red Castle") was an aircraft carrier built for the Imperial Japanese Navy (IJN), named after Mount Akagi in present-day Gunma Prefecture.  Though she was laid down as an "Amagi"-class battlecruiser , "Akagi" was converted to an aircraft carrier while still under construction to comply with the terms of the Washington Naval Treaty.  The ship was rebuilt from 1935 to 1938 with her original three flight decks consolidated into a single enlarged flight deck and an island superstructure.  The second Japanese aircraft carrier to enter service, and the first large or "fleet" carrier, "Akagi" figured prominently in the development of the IJN's new carrier striking force doctrine that grouped carriers together, concentrating their air power.  This doctrine enabled Japan to attain its strategic goals during the early stages of the Pacific War from December 1941 until mid-1942.

Japanese aircraft carrier Taihō: Taihō (大鳳 ) (meaning Great Phoenix), was an aircraft carrier of the Imperial Japanese Navy during World War II.  Possessing heavy belt armor and featuring an armored flight deck (a first for any Japanese aircraft carrier), she represented a major departure in Japanese aircraft carrier design and was expected to not only survive multiple bomb, torpedo, or shell hits, but also continue fighting effectively afterwards.

Democrația-class minesweeper: The "Democrația"-class minesweepers were a class of four minesweepers of the Romanian Navy, based on the design of the German M40 minesweeper but with different armament.  They were built at the Galați shipyard and launched in 1943, being armed with two German 88 mm naval guns.  Work on them was disrupted by the Soviet invasion of Romania in late 1944 and was only resumed in 1949.  Two of the ships, renamed "Democrația" and "Descătușarea", were completed in 1954, with "Desrobirea" completed in 1955 and "Dreptatea" in 1956.  By 1960, the two German naval guns were replaced by Soviet 85 mm naval guns.  The four ships were modernized in 1976, being mounted six AA guns of 37 mm and four machine guns of 14.5 mm, as well as mine launching rails, the ships being able to carry up to 50 mines each.  In 1993, the ships were re-designated as corvettes and renamed "Vice-Amiral Mihai Gavrilescu", "Vice-Amiral Ioan Bălănescu", "Vice-Amiral Emil Grescescu" and "Vice-Amiral Ioan Georgescu".  Ultimately, the ships were scrapped in 2001.

USS Archerfish (SS-311): USS "Archerfish" (SS/AGSS-311) was a "Balao"-class submarine.  She was the first ship of the United States Navy to be named for the archerfish.  "Archerfish" is best known for sinking the Japanese aircraft carrier "Shinano" in November 1944, the largest warship ever sunk by a submarine.  For this achievement, she received a Presidential Unit Citation after World War II.

Supporting paragraphs: Japanese aircraft carrier Shinano Yamato-class battleship
Answer: nine