This algorithm will calculate the lowest number that is evenly divisible by all of the numbers from 1-20. This is one of the Project Euler problems (ProjectEuler.net), which i have recently taken to playing with. I really enjoy thinking in a completely different way to my day job, and this is a great place to do that. Check it out below.
The code uses a do-while loop to increase the number to be tested from 1 to as high as is needed to allow the number to be divisable by 20 and all numbers below.