I once applied for a job and got back an email asking, "You are given 9 coins, one of which is heavier. Using a balance scale, how many weighings does it take

I once applied for a job and got back an email asking, "You are given 9 coins, one of which is heavier. Using a balance scale, how many weighings does it take to find the heavy coin?" I wrote back, "What is the maximum number of coins that you can process in 5 weighings to find the heavy one? If you know the answer to that, then you know that I Know the answer to your question." I didn't hear back. I guess they didn't understand the algorithm or they thought I was a wise-ass. Of course I could have been filtered through HR.