# Difficult Riddle **URL:** \ **Category:** The Game Room\ **Created:** [September 11, 2010, 10:32pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447 "2010-09-11T22:32:03Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 12, 2010, 12:52am UTC](https://boards.straightdope.com/t/difficult-riddle/553447/21 "2010-09-12T00:52:04Z")
You will too need three, if you want to [retroreflect](http://en.wikipedia.org/wiki/Retroreflector) a laser. ---
**Author:** ![The\_Bith\_Shuffle](https://avatars.discourse-cdn.com/v4/letter/t/ce73a5/32.png) [@The\_Bith\_Shuffle](https://boards.straightdope.com/u/The_Bith_Shuffle)\ **Post date:** [September 12, 2010, 1:03am UTC](https://boards.straightdope.com/t/difficult-riddle/553447/22 "2010-09-12T01:03:44Z")
> [@Lumpy](#): > > Mirrors. You use one to view your front. To view your back you need two, one facing your back and the other to see that mirror. You should never need three. The right answer! =) ---
**Author:** ![Enuma\_Elish](https://avatars.discourse-cdn.com/v4/letter/e/5e9695/32.png) [@Enuma\_Elish](https://boards.straightdope.com/u/Enuma_Elish)\ **Post date:** [September 15, 2010, 7:15pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/23 "2010-09-15T19:15:32Z")
Oh, I dunno. I think it only works if you are skinny. I think the more amply figured of us may need an extra mirror or two to peruse various aspects of our buttockal regions. ---
**Author:** ![Bosstone](https://avatars.discourse-cdn.com/v4/letter/b/22d042/32.png) [@Bosstone](https://boards.straightdope.com/u/Bosstone)\ **Post date:** [September 15, 2010, 7:20pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/24 "2010-09-15T19:20:57Z")
> [@The\_Bith\_Shuffle](#): > > > [@Lumpy](#): > > > > Mirrors. You use one to view your front. To view your back you need two, one facing your back and the other to see that mirror. You should never need three. > > The right answer! =) I suspected I was totally off. šŸ˜› ---
**Author:** ![Enderw24](https://avatars.discourse-cdn.com/v4/letter/e/ba9def/32.png) [@Enderw24](https://boards.straightdope.com/u/Enderw24)\ **Post date:** [September 15, 2010, 8:12pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/25 "2010-09-15T20:12:51Z")
> [@The\_Bith\_Shuffle](#): > > > [@Lumpy](#): > > > > Mirrors. You use one to view your front. To view your back you need two, one facing your back and the other to see that mirror. You should never need three. > > The right answer! =) Wait? Thatā€™s really the right answer? So why canā€™t you substitute ā€œinā€ for ā€œforā€? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 15, 2010, 8:17pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/26 "2010-09-15T20:17:40Z")
How many mirrors do you have in your back? ---
**Author:** ![Enderw24](https://avatars.discourse-cdn.com/v4/letter/e/ba9def/32.png) [@Enderw24](https://boards.straightdope.com/u/Enderw24)\ **Post date:** [September 15, 2010, 9:01pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/27 "2010-09-15T21:01:15Z")
> [@Chronos](#): > > How many mirrors do you have in your back? Donā€™t know. I donā€™t have a mirror to check back there. But itā€™s not in YOUR back. The riddle says in THE back. You can have a mirror in the front and in the back, no problemo. ---
**Author:** ![muldoonthief](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muldoonthief/32/3188_2.png) [@muldoonthief](https://boards.straightdope.com/u/muldoonthief)\ **Post date:** [September 15, 2010, 11:52pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/28 "2010-09-15T23:52:00Z")
> [@Enderw24](#): > > > [@Chronos](#): > > > > How many mirrors do you have in your back? > > Donā€™t know. I donā€™t have a mirror to check back there. > > But itā€™s not in YOUR back. The riddle says in THE back. You can have a mirror in the front and in the back, no problemo. But ā€œTwo (mirrors) in the backā€ wouldnā€™t let you see anything. Itā€™s two mirrors for the task of seeing your own back. ---
**Author:** ![Dead\_Cat](https://avatars.discourse-cdn.com/v4/letter/d/9fc29f/32.png) [@Dead\_Cat](https://boards.straightdope.com/u/Dead_Cat)\ **Post date:** [September 16, 2010, 7:12am UTC](https://boards.straightdope.com/t/difficult-riddle/553447/29 "2010-09-16T07:12:37Z")
I am SO glad this thread has a ā€œrealā€ answer - just when you think youā€™ve forgotten about the nightmare that was ā€œ14 k of g in a f p dā€, something pops up to remind you. Oh, and I may as well declare Iā€™ve just lost the game, while Iā€™m here. You can all send your thanks to the usual address. ---
**Author:** ![Uncle\_Brother\_Walker](https://avatars.discourse-cdn.com/v4/letter/u/f08c70/32.png) [@Uncle\_Brother\_Walker](https://boards.straightdope.com/u/Uncle_Brother_Walker)\ **Post date:** [September 18, 2010, 3:39am UTC](https://boards.straightdope.com/t/difficult-riddle/553447/30 "2010-09-18T03:39:50Z")
I use three mirrors to cut my hair. The one in the front, and one on each side (these two are hinged so I can see the back of my head and cut straight). Technically, I use all three, but only use the side two in concert to see the back. I only need one to cut the top and sides. The tailor I use has a three mirror set so I can see what adjustments heā€™s making to the seat of my pants and the back of the pants cuffs, so I guess thatā€™s three for the back. I was thinking propellers. Thereā€™s sometimes one in front, and sometimes thereā€™s two in the back without the one in the front, like the A-10 Warthog. (I know the A-10 has turbines instead of props, but Iā€™m sure thereā€™s some WWII plane that has two in the back.) Sometimes they have four, but I donā€™t think Iā€™ve ever seen a plane with three props. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [September 18, 2010, 6:50am UTC](https://boards.straightdope.com/t/difficult-riddle/553447/31 "2010-09-18T06:50:09Z")
> [@Uncle\_Brother\_Walker](#): > > I was thinking propellers. Thereā€™s sometimes one in front, and sometimes thereā€™s two in the back without the one in the front, like the A-10 Warthog. (I know the A-10 has turbines instead of props, but Iā€™m sure thereā€™s some WWII plane that has two in the back.) Sometimes they have four, but I donā€™t think Iā€™ve ever seen a plane with three props. Never heard of a [Ford Tri-Motor](http://en.wikipedia.org/wiki/Ford_Trimotor)? Or a [Ju-52](http://en.wikipedia.org/wiki/Ju-52)? Now I grant you that the [Flying Shoe](http://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_138) was an oddity, but the Italian airforce had several [three](http://en.wikipedia.org/wiki/Savoia-Marchetti_SM.81)-[engined](http://en.wikipedia.org/wiki/Savoia-Marchetti_SM.79) [bombers](http://en.wikipedia.org/wiki/CANT_Z.1007), whereas Iā€™m struggling to think of any twin-prop pushers outside of _Raiders of the Lost Ark_ for this timeframe; twin-prop planes have overwhelmingly been tractor configuration, and where pushers have been used at all, they are almost invariably single-engined. ---
**Author:** ![Ximenean](https://avatars.discourse-cdn.com/v4/letter/x/aca169/32.png) [@Ximenean](https://boards.straightdope.com/u/Ximenean)\ **Post date:** [September 18, 2010, 12:50pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/32 "2010-09-18T12:50:20Z")
I was thinking of the letter I in US state names. Sometimes one for the front (Indiana etc.), sometimes two for the back (Hawaii), but never three (consecutively). But it fails the substitution test - you could just as easily, and probably would, say _at_ the front. ---
**Author:** ![Zebra](https://avatars.discourse-cdn.com/v4/letter/z/c0e974/32.png) [@Zebra](https://boards.straightdope.com/u/Zebra)\ **Post date:** [September 18, 2010, 3:54pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/33 "2010-09-18T15:54:47Z")
I guess all those department stores with 3 way mirrors are fools. ---
**Author:** ![Bootis](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@Bootis](https://boards.straightdope.com/u/Bootis)\ **Post date:** [September 18, 2010, 9:06pm UTC](https://boards.straightdope.com/t/difficult-riddle/553447/34 "2010-09-18T21:06:38Z")
Easier, more convenient with 3 or more? Sure, but not necessary. [Previous page](https://boards.straightdope.com/t/difficult-riddle/553447.md?page=1)