You are correct in your suspicion, there are no chemical symbols that consist of more than two letters. On the other hand, there are molecules with double-digit numbers of atoms, e.g. C6H12O6.

I have implemented random tests.

Would you mind explaining how input modification can be done? I thought that I had addressed this issue.

BOOKSETCOSTS has been defined. Sorry for the oversight.

Ok. Thanks for picking me up on this.

However, it is misleading that the conventions page (i.e. https://www.codewars.com/topics/kata-best-practices#convention) includes a function named binomial_distribution_rand.

I have updated the Kata's Description. Is the rule now clear?

Thank you for the instructions.

I would like to add random tests. How do I do that? Are you able to direct me to some instructions?

I enjoyed this Kata. Thank you