18 x 3 = 54mm (close enough to 55mm for them to call it "3X")

There's still not enough info to answer your question. How close you can get to something depends on how close that particular lens will focus. It might be about 2' or 3', but check the lens and see what it says. Zooming in is something different - a 55mm lens isn't particularly long on a digital SLR.