+/- 4 X ISAD X (alt/1000)
eg: for an approach in -10deg temps with an OM height of 1500 feet:
-4*-25*1.5=150ft OVERREAD.
Or do is I do, ditch the minus signs, just use 4*isad*alt/1000 and remember that colder will overread/warmer will underread.
So, to answer your question:
4*40*1.76=281
so on outermarker crossing, your altimeter should indicate 2040'.
Thank ChimbuChuckles for teaching me that one!
**Edited to correct ISAd due to the effects of no sleep**