Off & Of

[sandiemoore]

Save 10% on 8 off the same item. Should this be of or off?

[Quizmonster]

Of.

[yardie]

it is definitely 'of'

[maximo]

10% off : off means "taken out, removed...as in "take off your jacket""

10% off on 8 of the same item : of in the sense of "from" or genitive form ( my mum's cat = the cat of my mum )

That's the way I use to remember the rule, as it's not my first language.