Doctor Who Series 11: 10 Big Questions After Episode 5
2. What's In A Number?
As she prepares to set the bomb, the Doctor asks Yaz to think of a number. We don’t know if her choice of 51 was entirely random, or if it had some significance such as a house number. It could just have easily been a subconscious reference to Area 51 given Yaz’s encounters with aliens, but whatever the reason behind it the Doctor certainly approves of her choice.
For starters, it’s a pentagonal number, which delights the Doctor no end, elevating her geek status even higher and no doubt delighting any viewer who could have made the same connection. The Doctor, who would probably also describe herself as a Doctor of Geology (as long as River Song isn’t around), also points out that 51 is the atomic number of the mineral Antimony. It’s somewhat ironic given that from ancient times antimony was used for medicinal purposes. Pliny the Elder distinguished between male and female forms, with the latter being the stronger of the two – which in the context of the episode and this series of Doctor Who as a whole may not be entirely coincidental.
Back in 2007 Chibnall’s first Doctor Who script was the 24 inspired 42. From the point that the Doctor and her friends wake up on the hospital ship, The Tsuranga Conundrum is more or less also occurring in real time (check out how long those seven minutes take on screen). The total running time is, you guessed it, 51 minutes.