27 was a number.
At one point during their failure, a Kroton calculated they would have to reserve power for 27 further minutes before it exhausted. (TV: The Krotons [+]Robert Holmes, Doctor Who season 6 (BBC1, 1968-1969).)
Vega 3 was 27 light-years from Earth. (PROSE: K9 and the Beasts of Vega [+]Dave Martin, The Adventures of K9 (Sparrow Books, 1980).)
Through use of a magnetron, the New Dalek Empire transported 27 stolen planets from across time and space to the Medusa Cascade, where they collectively served as an engine for the Daleks' reality bomb. (TV: The Stolen Earth [+]Russell T Davies, Doctor Who series 4 (BBC One, 2008)./Journey's End [+]Russell T Davies, Doctor Who series 4 (BBC One, 2008).)
When arguing with Clara Oswald over who should hack Rosemary Kizlet's software, the Eleventh Doctor, among other factors, listed his 27 brains as to why it should be him. When Clara expressed doubt about this, he admitted to it being an exaggeration. (TV: The Bells of Saint John [+]Steven Moffat, Doctor Who series 7 (BBC One, 2013).)
The Twelfth Doctor identified at least 27 different species living in Trap Street. (TV: Face the Raven [+]Sarah Dollard, Doctor Who series 9 (BBC One, 2015).)
The Ninth Doctor calculated that he has saved every planet in the known universe a minimum number of 27 times. (TV: The Curse of Fatal Death [+]Steven Moffat, Doctor Who television episodes (BBC One, 1999).)
Bowie Base One geologist Mia Bennett was sorrowfully noted by the Tenth Doctor to be "only 27 years old" by the time of her destined death on the base in 2059, although she ultimately survived when the Doctor defied fixed history to save her and two other colleagues. (TV: The Waters of Mars [+]Russell T Davies and Phil Ford, Doctor Who Autumn Special 2009 (BBC One, 2009).)
Chronon, (WC: 14682 UNIT Field Log [+]UNIT Field Log (2020)., 14683 UNIT Field Log [+]UNIT Field Log (2020)., 14684 UNIT Field Log [+]UNIT Field Log (2020).) or cronon (WC: 14681 UNIT Field Log [+]UNIT Field Log (YouTube, 2020).) and artron energy readings during the recording of UNIT field logs included 17%, (WC: 14682 UNIT Field Log [+]UNIT Field Log (2020).) 18%, 19%, (WC: 14681 UNIT Field Log [+]UNIT Field Log (YouTube, 2020)., 14682 UNIT Field Log [+]UNIT Field Log (2020).) 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, (WC: 14682 UNIT Field Log [+]UNIT Field Log (2020).) 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, (WC: 14682 UNIT Field Log [+]UNIT Field Log (2020)., 14684 UNIT Field Log [+]UNIT Field Log (2020).) 90%, (WC: 14682 UNIT Field Log [+]UNIT Field Log (2020)., 14683 UNIT Field Log [+]UNIT Field Log (2020).) 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, 101%, 102%, 103%, 104%, 105%, 106%, and, in the case of Chronon energy, 107%. (WC: 14683 UNIT Field Log [+]UNIT Field Log (2020).)