In the original Blade Runner Deckard asks Rachel over a hundred questions before he confirms she's a replicant. However, Rachel is implied to be a special case. When administering the Voight-Kampff test, how many questions do Blade Runners normally ask before they're satisfied that someone being tested is human?
It typically requires 20 to 30 questions.
From the script of Blade Runner:
Deckard: One more question. You're watching a stage play. A banquet is in progress. The guests are enjoying an appetizer of raw oysters. The entree consists of boiled dog.
Tyrell: Would you step out for a few moments, Rachael -- Thank you.
Deckard: She's a replicant, isn't she?
Tyrell: I'm impressed. How many questions does it usually take to spot them?
Deckard: I don't get it Tyrell.
Tyrell: How many questions?
Deckard: Twenty, thirty, cross-referenced.
Tyrell: It took more than a hundred for Rachael, didn't it?
Deckard: She doesn't know?!
Tyrell: She's beginning to suspect, I think.
Deckard: Suspect? How can it not know what it is?
Tyrell: Commerce, is our goal here at Tyrell. More human than human is our motto. Rachael is an experiment, nothing more. We began to recognize in them strange obsession. After all they are emotional inexperienced with only a few years in which to store up the experiences which you and I take for granted. If we gift them the past we create a cushion or pillow for their emotions and consequently we can control them better.
Deckard: Memories. You're talking about memories.
You can read the complete script here...
This dialogue also actually appears in the finished film. Watch it here
The line is spoken at around 1 minutes 20 seconds into the clip.