Say you have a perfectly round pie. You take an infinitely small slice from that pie. Is it still a whole pie?
Here's an easier one to grasp, using exponentials. Say you have two graphed points, point A and point B. You move point B half way closer to point A, to shorten the distance between them by half, so they are %50 as far from each other as before. Say you take away half the distance between them once more...and once more...and once more...and so on. The points will keep getting closer to each other each time, but they will never meet, no matter how many times you divide by half. And, as the distance between the points will never reach zero after dividing the distance in half infinity times, 0.9~ will never equal 1. It will keep getting closer, but never get there.