What 2 means
The shortcut plays on how two sounds in English.
“Two,” “to” and “too” are pronounced the same in English, so the digit can stand in for any of them. Read 2day as “today,” g2g as “got to go,” and 2u as “to you.” The digit is doing a word's job, not counting.
Can I use 2 in formal writing?
Yes for numbers; spell out to and too. In applications, reports, and schoolwork, texting substitutions look informal. Numerical uses such as times, scores and addresses are a separate matter.
Neutral as a numeral; casual as an English spelling shortcut.
Don't replace to or too with 2 in formal writing.
Don't confuse it with
4Combination ideas
3Questions people ask
1What does number 2 mean as slang?
It can mean defecation in the English phrase “number two.” Don't automatically read a lone 2 as a bathroom reference.
How to type 2
2\0032Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.

