







IO = 2

IO is visibly similar to 10 (it is also a possible translation of the numbers from Leet).



10 is 2 in the binary numeral system.

10 = 0*2^0 + 1*2^1 = 2





Binary base is already used in the episode:

In the fake code tied to the final face off.



SHERLOCK: Every beat is a one, every rest is a zero. Binary code.



As a clue released before the episode to be translated from binary ASCII CODE (read here).



01110100 01101000 01100101 01110010 01100101 00100000 01101001 01110011 00100000 01101110 01101111 00100000 01101011 01100101 01111001 = “there is no key”

During a sequence included in Moriarty’s criminal stunt:

As possible easter egg included in the time at which Moriarty starts his criminal stunt, 11:00:



As a possible easter egg in this shot with an on/off switch:





A code similar to IOU was used in The Private Life Of Sherlock Holmes. IOE turned out to be 301, so the IO was actually a 01.











U = YOU

U stands for YOU both in common English and explicitly in the episode as IOU menas “I Owe You”.





The attention to YOU as a word tied to IOU is brought back in The Abominable Bride, written in a similar stile as IOU and differing only one letter.





2 AND YOU - MENTIONS

Here’s some significant mentions of 2 and YOU together in the dialogue:

SHERLOCK: I mean TWO of YOU. All TWO of YOU.



MORIARTY: There’s TWO of YOU





There are also several probably not significant mentions of “YOU TWO” and one of “YOU in TWO”.

Here’s some significant mentions of something having TWO:

SHERLOCK: Janus Cars. The clue’s in the name.

JOHN: The god with TWO faces.



SHERLOCK: Why has it got TWO fronts?

Not a mention, as it is taken from ACD canon, but an interpretation, but 221 as Two to One also fits this scheme.

There is more in general a theme of duality in the series, like there being TWO bottles, TWO buildings, TWO types of fan…





2 AND YOU - POSSIBLE MEANINGS

Moriarty saying to Sherlock TWO and YOU, might be a reference to:

Sherlock and John as a couple;



Sherlock and a sibling, possibly a twin;



Sherlock having a double personality disorder.

REFERENCES

Ariane DeVere’s Sherlock Transcripts