In the XXI. century there is a rising, scientific interest in the enlarging universe, multiverse and parallel universes. This book introduces a newer concept of numbers: the exploded numbers which discuss this problem by the instruments of pure mathematics. It enlightens that the borderless universe has bounds. It models the place of our universe in the multiverse. Finally it contains never seen extra-geometry which differentiates from Euclidean-, Bólyai-Lobachevsky- and Gömbi-geometries.