I found this problem on the internet: What is the largest chain of numbers that complies with that every number in the chain/list is a divisor divisor in the next number. For example 1 - 6 - 18 - 72 (this one is a chain of 4 numbers) and 5 - 25 - 100 (this one is a chain of 3 number) So the question is how many numbers do the longest chain contain - IF you may not use numbers higher than 1000?
I think it is 1 - 2 - 4 - 8 - 16 - 32 - 64 - 128 - 256 - 512, which contains 10 numbers. What do you think?