This is a sequence (not "series" unless they are added together, with + signs between). Note that the 2nd term - 1st term = 8-3 = 5 Note that the 3rd term - 2nd term = 13-8 = 5 Note that the 4th term - erd term = 18-13 = 5 That tells us that this is an arithmetic sequence with common difference, d=5. The formula for the nth termof an arithmetic sequence is Divide both side by 5 So , the 444th term. Edwin