Frank Percy Doel (14 July 1908 – 22 December 1968) was an antiquarian bookseller for Marks & Co in London, England who achieved posthumous fame as the recipient of a series of humorous letters from American author Helene Hanff, to which he scrupulously and, at first, very formally replied.
 The shop where he worked was at 84 Charing Cross Road, the title of a bestselling 1970 novel written by Hanff which became a cult classic, a 1981 stage play, and a 1987 film starring Anthony Hopkins as Doel and Anne Bancroft as Hanff.
Marks & Co, also incorrectly referred to as "Marks & Company" or colloquially as "84", was a well-known antiquarian bookseller located at Cambridge Circus - 84, Charing Cross Road, London.
Postal codes in Germany, "Postleitzahl" (plural Postleitzahlen, abbreviated to PLZ; literally "postal routing number"), since 1 July 1993 consist of five digits.
 The first two digits indicate the wider area, the last three digits the postal district.
A circular prime is a prime number with the property that the number generated at each intermediate step when cyclically permuting its (base 10) digits will be prime.
 For example, 1193 is a circular prime, since 1931, 9311 and 3119 all are also prime.
 A circular prime with at least two digits can only consist of combinations of the digits 1, 3, 7 or 9, because having 0, 2, 4, 6 or 8 as the last digit makes the number divisible by 2, and having 0 or 5 as the last digit makes it divisible by 5.
 The complete listing of the smallest representative prime from all known cycles of circular primes (The single-digit primes and repunits are the only members of their respective cycles) is 2, 3, 5, 7, R, 13, 17, 37, 79, 113, 197, 199, 337, 1193, 3779, 11939, 19937, 193939, 199933, R, R, R, R, R, R, R, and R, where R is a repunit prime with "n" digits.
 There are no other circular primes up to 10.
 A type of prime related to the circular primes are the permutable primes, which are a subset of the circular primes (every permutable prime is also a circular prime, but not necessarily vice versa).
Codice di Avviamento Postale (Postal Sending Code) is the Italian post code numeric system, consisting of five digits, such as 20121 Milan.
 Created in 1967, they are commonly known as CAP.
 The first two digits denote the administrative province (two provinces when a province has been split after 1967); the third digit shows if the town is the chief-town of the province (odd number, usually 1 or 9, e.g. 07100 Sassari) or not (even, usually 0 or 8, e.g. 10015 Ivrea); the last two digits the specific town or village or the delivery post office (only in new provinces created after 1992).
 In main cities like Rome, Milan, Naples, Venice the last digits designate the urban postal district (usually 00 or 70 in minor provincial chief-towns).
 San Marino and the Vatican City are integrated into the Italian postcode system.
Liu Hui's π algorithm was invented by Liu Hui (fl.
 3rd century), a mathematician of the Wei Kingdom.
 Before his time, the ratio of the circumference of a circle to its diameter was often taken experimentally as three in China, while Zhang Heng (78–139) rendered it as 3.1724 (from the proportion of the celestial circle to the diameter of the earth, 92/29 ) or as formula_1.
 Liu Hui was not satisfied with this value.
 He commented that it was too large and overshot the mark.
 Another mathematician Wan Fan (219–257) provided π ≈ 142/45 ≈ 3.156 .
 All these empirical π values were accurate to two digits (i.e. one decimal place).
 Liu Hui was the first Chinese mathematician to provide a rigorous algorithm for calculation of π to any accuracy.
 Liu Hui's own calculation with a 96-gon provided an accuracy of five digits: π ≈ 3.1416 .
The "Solent"-class lifeboat was essentially a steel-hulled version of the 48ft 6in "Oakley"-class self-righting lifeboat and was sometimes referred to as the Oakley "Mark III".
 Solent Operational Numbers followed on from the first three 48ft 6in Oakleys and were interrupted by the last two Oakleys (48-12 and 48-13).
 The operational numbers of the "Solent"-class had three digits in the suffix to indicate a metal hull (as with Clyde, Waveney, Thames, Tyne classes, one Arun class and the first eleven Merseys).
 Two digits indicates a wooden, GRP or FRC hull.
Smithsonian trinomials are unique identifiers assigned to archaeological sites in many states in the United States.
 They are composed of one or two digits coding for the state, typically two letters coding for the county or county-equivalent within the state, and one or more sequential digits representing the order in which the site was listed in that county.
 The Smithsonian Institution developed the site number system in the 1930s and 1940s.
 (Trinomials are now assigned by the individual states.)
 The 48 states then in the union were assigned numbers in alphabetical order.
 Alaska was assigned number 49 and Hawaii was assigned number 50 after those states were admitted to the union.
 There are no Smithsonian trinomial numbers assigned for the District of Columbia or any United States territories.
A new wagon numbering system was adopted in Indian Railways in "2003".
 Wagons are allocated 11 digit numbers making it easy for identification and computerization of the wagon information.
 The first two digits indicate "Type of Wagon", the third and fourth digits indicate "Owning Railway", the fifth and sixth digits indicate "Year of Manufacture", the seventh through tenth digits indicate "Individual Wagon Number", and the last digit is a "Check digit".
Solace is a 2015 American mystery thriller film directed by Afonso Poyart and starring Anthony Hopkins, Colin Farrell, Jeffrey Dean Morgan and Abbie Cornish.
 The film's script was originally planned and developed as a sequel to the 1995 thriller film "Se7en", but the idea was eventually scrapped, and "Solace" was completed instead.
 The film was released on December 16, 2016, by Lionsgate Premiere.
 The film is about a psychic doctor, John Clancy (Anthony Hopkins), who works with an FBI special agent (Jeffrey Dean Morgan) in search of serial killer Charles Ambrose (Colin Farrell).

Question: Which London bookseller was the subject of a film starring Anthony Hopkins and was often referred to colloquially as a number comprised of two digits?
Answer: Marks & Co