Hail Stone Number Cost: $4 Get the full version     Trial version     Developer's Website Contacting third-party download site please wait. If your download does not start, click here, or get the full version Descriptions Hail Stone Number: Hailstone Number checker allows you to process an integer that you enter in. The challenge is to see whether or not you can discover a sequence that does not get stuck in the never ending repeating pattern of 421421421421.... This simple mathmatical treat has plagued university students across America over 20 years ago. At one time, a rumor even spread that spies had started this brain teaser to keep math students from their studies.