Let us look at the difference in the terms of the series 600 - 519 = 81 406 - 370 = 36 370 - 345 = 25 345 - 329 = 16 The pattern observed is that the difference amongst consecutive terms is the square of natural numbers. Hence, the difference between 519 and the next number is 64.  So, the required term equals 519 - 64 = 455