I am not sure if this is the right sub-forum to post this question in or not, if not I appologize for posting in the wrong place - it looked like the most likely forum to be the correct one. In a sci-fi book I was reading, the author talked about an 'artificial symbiote' being created by 15 molecular pieces aligned correctly, which had been stolen from the villians. He said the possible combinations were in the millions, and that if you tested one combination per second, it would take over 4,000 years. This has been nagging at me for quite a while, I did what I thought was the proper calculation to find this out, to check his figures and I come up with much different numbers. So I was wondering if someone could tell me if I am not calculating this correctly. First, I decided you would have to calculate 15 to the 15th power, 15^15, to get the number of possible combinations. When I do this, I get over 437 Quadrillion possible combinations 437,893,890,380,859,000. Next I calculated the number of seconds in a year, I got 31,536,000. Then I divided the number of calculations by the number of seconds in a year. Instead of 4,000 I got 13,885,524,174.94 13 billion is a lot different than 4,000 so I am puzzled. Am I calculating this wrong, or is the author? Thanks for any light you can shine on this problem for me.