We've already checked on and minus forest to we've already checked that 1 to 5 can't be done, even though five is two plus three and minus five is one which can't be written as a sum of prime factors, event and so this condition of whether or not the number of test tubes and the number of missing spots can be written as a sum of prime factors of the number of holes is exactly when you can balance a centrifuge, which is something we understand really well, right?