My name is Joseph and I have a question I hope someone can help me with.
Does anyone know if there is a rule/trick to knowing when an integer is divisible by 7 or 13. Is there a good source for these rules which would include a proof or explanation ? Are there more divisibility rules I can glean? I've tried some books on number theory but can't find a complete list.
I have the rules for 2, 3, 5, 8, and 11. (are there more?)