The LSAT scoring is a notoriously weird thing.
Some years you can miss 12 questions and get a 170.
Others, you might miss 9 questions and not reach that coveted score.
The exam difficulty varies across years and to make it "fair" they adjust the scores to standardize them across the years.
The problem with this is that you might take the exam feeling like you did really well because it was easy...
And get a 160 because it was easy for everyone else also.
There are a total of ~100 questions and each correct answer adds 1 point to your raw score. (You're not penalized for guessing.)
On the right you can see an example of the conversion graph that might be used.
The one on the right is for the June 2007 exam.
However, the numbers can change which is why it's so hard to say how many questions you can miss and still get the score you want.