23 was a number.
While observing a rocket from the Wheel, Tanya Lernov read readings so that Zoe Heriot could carry out a mental calculation. The lineal reading was 198.42 metres at 23 degrees latitude and 190.03 metres at 24 degrees latitude. (TV: The Wheel in Space)
Danny Pink dug twenty-three wells during his time as a soldier. (TV: Listen)
According to one account, Zoe Heriot went into a coma which lasted twenty-three years after the Second Doctor linked her to the TARDIS' telepathic circuits. (PROSE: Dream a Little Dream for Me)
Abslom Daak was sentenced to Exile D-K after being found guilty of "23 charges of murder, pillage, piracy, massacre and other crimes too horrible to bring to public attention." He was told the life expectancy of a Dalek Killer was 2 hours, 32 minutes and 23 seconds. (COMIC: Abslom Daak... Dalek Killer)
Hex first met the Seventh Doctor and Ace on his 23rd birthday. (AUDIO: The Harvest)
Chronon, (WC: 14682 UNIT Field Log, 14683 UNIT Field Log, 14684 UNIT Field Log) or cronon (WC: 14681 UNIT Field Log) and artron energy readings during the recording of UNIT field logs included 17%, (WC: 14682 UNIT Field Log) 18%, 19%, (WC: 14681 UNIT Field Log, 14682 UNIT Field Log) 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) 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, (WC: 14682 UNIT Field Log, 14684 UNIT Field Log) 90%, (WC: 14682 UNIT Field Log, 14683 UNIT Field Log) 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)