There's a whole lot of BS floating around the Internet about how a small-sensor DSLR turns a 400mm lens into a 600mm lens through a magical "Multiplier Factor".
This is rubbish.
The focal length of a lens does not change when it is mounted on a DSLR. The angle of view may be reduced (due to the sensor only recording the center of the image) but that's all.
If you read an Internet review which perpetuates this myth, consider the whole article unreliable. If a camera salesperson tells you this, walk away.
Don't be a victim of this hoax. There are too many already.
You do seem to be very bothered by this multiplier factor business - but I can't see why.
Obviously you're right, the lens doesn't change when you mount it on a digital camera. It is nontheless true that a lens from a 35 mm camera won't produce the same results on a digital SLR. I don't think that anyone, review auythors or sales staff are trying to hoax us. The multipier factor is just a way of explaining the different effect.
Mike, I'm bothered by the multiplier factor business because I don't like it when people lie to me in order to get my money. Where I come from it's called "fraud" and it's a hangin' offence.