My question may come as a surprise to many people but I have not understood the importance of zero and its significance. How can nothing be something? Why do we have zero as a number? If it's used for measuring then we can very well do without zero, for example if there is a fellow counting pebbles then after say 9 pebbles he can count 11,12 etc. upto infinite. Also I don't understand the reason for negative numbers. How can something be less than nothing???