The order of numbers seems self-evident. We add up and down, order and structure, without asking ourselves why this sequence is so crucial. The idea that 7 comes after 6 and before 8, that 345 has a different meaning than 453, is so ingrained in our perception that it is rarely questioned. But how fundamental is the order of numbers? And more importantly: where does the wrong order lead to real problems? This question is difficult to answer, because numbers generally arrange themselves neatly in the universe of logic. Yet, if we really dig deep, we find situations where the right number order means the difference between a working system and complete chaos.