The Gold Bar Logic Puzzle!

[Image courtesy of Pinterest.]

As many of our long-time readers know, we’re happy to accept the challenge of any brain teaser, riddle, mind tickler, or puzzle that is bedeviling one of our fellow PuzzleNationers.

So when someone suggested that I tackle the Birthday Paradox brain teaser, I said it was a terrific idea for a post. (As such, I mentioned it in the Facebook post I write every Monday running down the upcoming blog posts for the week.)

I sat down to write it… and I had this unshakable sense of deja vu. I thought maybe I was just overly familiar with the topic, since I’ve explained it to other puzzle fans before, just not here.

But the idea just kept nagging at me. And with good reason.

A quick blog search later, and it turns out the Birthday Paradox brain teaser is a terrific idea for a post. Which is why I wrote a blog post about it. Nearly four years ago.

My apologies to everyone expecting the Birthday Paradox brain teaser today, but I’d rather not double-down on this faux pas.

Thankfully, that wasn’t the only brain teaser someone has suggested to me recently.

[Image courtesy of Law.com.]

So, in lieu of a brain teaser we’ve already covered, let’s look at another devious brain teaser. Join me as we tackle the challenge of the Gold Bar Logic Puzzle.

You’re out traveling and stumble upon a quaint little hotel.

You decide to stay there for seven nights. For some reason, the only currency you have with you is a solid gold bar that is notched into seven separate segments, sort of like a candy bar.

[Kinda like this. But gold.
Image courtesy of American Icons Temple.]

Luckily, the front desk agrees to let you pay in gold segments. You need to pay the hotel daily for each night you stay.

What is the fewest number of times you must cut your gold bar so that one segment is paid to the hotel every day?

I’ll give you some time to consider the puzzle before breaking down the answer for you.

Good luck!

Hint: You are allowed to ask for change, but the only gold they have is what you’ve given them. This isn’t a quaint little inn in Dubai.

And no, you can’t just give the hotel clerk the whole bar (or what hasn’t been cut off previously) each day and make the clerk do the cutting. The whole idea is that you’re the one doing the cutting.

Did you get it? Good!

And if not, no worries, I’ll meet you halfway.

The answer is two cuts. Just two.

Can you figure out how to cut the gold bar to make your stay work out?

Okay, hopefully you’ve unraveled the puzzle by now, because it’s answer time. Here we go!

You need to cut the gold bar in order to pay the clerk each night, but you don’t need to waste a lot of time slicing through gold. You just need to be clever in how you distribute it.

  • Night One: Cut off one notch of gold from your bar and pay the clerk. You have 6 notches of gold left.
  • Night Two: Cut off two notches of gold from your bar and pay the clerk. Since you’ve paid double, the clerk gives you back your notch from Night One as change. You have 5 notches of gold left (the block of 4 notches and the single notch).
  • Night Three: Pay the clerk with the single notch of gold. You have 4 notches of gold left (in one uncut block).
  • Night Four: Pay the clerk with your four-notch bar of gold. Since you’ve overpaid, the clerk gives you back your notch from Night Three and the two-notch block from Night Two. You have 3 notches of gold left.
  • Night Five: Pay the clerk with the single notch of gold. You have 2 notches of gold left (in one uncut block).
  • Night Six: Pay the clerk with the two-notch block of gold. Again, you’ve paid double, so the clerk gives you back your single-notch block.
  • Night Seven: Pay the clerk with the single notch of gold.

Two cuts, seven nights. Pretty efficient if you ask me!


So, how did you do? Let us know in the comments below, we’d love to hear from you!

[Note: In doing a little research, it appears this logic puzzle was created by Ray Epstein and Ben Kovler, and it appears in their book Fundrum My Conundrum: A Book of Riddles.]


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