Funny that you mention fractions, I started learning them a week ago. Though I can't say I even encountered decimal 1/7 in real life...
If you read a comment on LW that's downvoted to -5 and says "14% positive" this means it's received 1 upvote out of 7 total.
If you remember all of the repeating digits (142857) then you can also identify 28%, 42%, 57%, 71%, and 85% as 2/7, 3/7, 4/7, 5/7, and 6/7, respectively.
This is the public group instrumental rationality diary for July 1-15.
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