Let X be any positive number. Let x be the sequence xn = 1/n. Then, an N can be found such that 1/n < X for any n > N. Hence, by the definition of less than in hyperrational sequences; x < X. Such hyperrational sequences are called infinitesimal. A sequence, x, is infinitesimal if |x| < X for any positive X. If x > 0, x is called a positive infinitesimal. If x < 0, x is called a negative infinitesimal. Normally zero is the only number with that property. Also, we have infinitesimals smaller than other infinitesimals, e.g. 1/n^2 < 1/n, except when n = 1.