Q: whats the divisibility rule for seven and eleven again? i keep on forgetting
A: there's no rule, but there's a strategy. for example, take 43288. to see if it's divisible by 7, modify it by 7s until you recognize it as divisible by 7 or not. and you can also divide by anything, if that's convenient. Right where it is, we can subtract 28, which will knock off a zero. 43260, and divide by 10. is 4326. this seems way easy to cut in half, which is a legit transformation, but for now i'll skip that. if you want, you could add 14, to get 4340 -->434. then subtract 14, is 42. bingo, that's a multiple of 7. so 43288 is divisible by 7.