# answers to odd numbered problems **URL:** \ **Category:** Factual Questions\ **Created:** [November 15, 2004, 11:29pm UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952 "2004-11-15T23:29:29Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![prolific9](https://avatars.discourse-cdn.com/v4/letter/p/e99b99/32.png) [@prolific9](https://boards.straightdope.com/u/prolific9)\ **Post date:** [November 15, 2004, 11:29pm UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/1 "2004-11-15T23:29:29Z")
in all of my physics/math/chemistry books the back of the book contains the answers to only the odd numbered problems … why don’t they include the answers to the even numbered problems ? after all theres no point in doing the even numbered questions if there is no way to check if your answer is correct or not … could it be because they want to allow teachers to assign even numbered problems and therefore the students wouldn’t have access to the even numbered answers ? 😃 ---
**Author:** ![Berkut](https://avatars.discourse-cdn.com/v4/letter/b/a88e57/32.png) [@Berkut](https://boards.straightdope.com/u/Berkut)\ **Post date:** [November 15, 2004, 11:32pm UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/2 "2004-11-15T23:32:10Z")
> [@prolific9](#): > > could it be because they want to allow teachers to assign even numbered problems and therefore the students wouldn’t have access to the even numbered answers ? 😃 Yep. ---
**Author:** ![prolific9](https://avatars.discourse-cdn.com/v4/letter/p/e99b99/32.png) [@prolific9](https://boards.straightdope.com/u/prolific9)\ **Post date:** [November 15, 2004, 11:37pm UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/3 "2004-11-15T23:37:29Z")
they might just use that as an excuse to not work out the answers for the even numbered questions … unless they provide a special teachers edition of the books with all the answers :smack: ---
**Author:** ![Jurph](https://avatars.discourse-cdn.com/v4/letter/j/50afbb/32.png) [@Jurph](https://boards.straightdope.com/u/Jurph)\ **Post date:** [November 15, 2004, 11:53pm UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/4 "2004-11-15T23:53:47Z")
I had a professor who assigned such a text. Homework was “problems eleven through twenty, odds to be graded.” You didn’t have to hand in the evens at all – he even said as much! – but he _strongly encouraged_ us to work them nonetheless. Usually each odd problem is the easy demonstration of a technique, and the even one following it includes a wrinkle. The evens would then show up “in disguise” (think Anne Hathaway in overalls and glasses) on the exam. If you’d done them before, you’d breeze through the exam. A variation on this theme involves problem sets that include _almost_ every problem; the evens from the gaps end up on the exam. So, if you’re assigned the following problems for homework: 3-6,11,12,17-20,23,24,29,30 …then you can expect to see 8, 10, 14, 16, 26, 28, or 32 on the exam. You should be able to look at the first four and do them in your head – or at least describe the method – within five seconds of reading the problem. The other three you should work ahead of time apart from your study partner, and then check answers with each other. And of course, if you’re assigned an odd and not its even partner, work the even one in parallel with a buddy before the exam. You’ll thank me later! ---
**Author:** ![Happy\_Lendervedder](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_lendervedder/32/8488_2.png) [@Happy\_Lendervedder](https://boards.straightdope.com/u/Happy_Lendervedder)\ **Post date:** [November 15, 2004, 11:54pm UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/5 "2004-11-15T23:54:53Z")
I always thought it was so your could make sure you’re doing it right, without giving you _all_ the answers. The process is as important as the answer in that stupid, stupid math. ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [November 15, 2004, 11:58pm UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/6 "2004-11-15T23:58:30Z")
Some teachers will assign the odds one night and then the evens the next, so that you can sort of use them as a crutch, then get rid of the crutch. But I’m pretty sure the main reason is so that you have to actually do some work, instead of just copying, which many people would do. Bad idea, of course, as it wastes time and teaches nothing, but a lot of people would do that. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [November 15, 2004, 11:59pm UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/7 "2004-11-15T23:59:03Z")
> [@prolific9](#): > > they might just use that as an excuse to not work out the answers for the even numbered questions … unless they provide a special teachers edition of the books with all the answers :smack: That’s the teacher’s edition for you. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [November 16, 2004, 12:33am UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/8 "2004-11-16T00:33:42Z")
In the math classes I teach, I assign (and collect) a mixture of odd and even-numbered problems. Occasionally students hand in papers on which answers to odd-numbered problems miraculously appear out of nowhere, with no indication as to how the student came up with these answers. For some reason, this never seems to happen with the even-numbered problems… ---
**Author:** ![Roches](https://avatars.discourse-cdn.com/v4/letter/r/bc8723/32.png) [@Roches](https://boards.straightdope.com/u/Roches)\ **Post date:** [November 16, 2004, 12:41am UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/9 "2004-11-16T00:41:19Z")
Yeah, the teacher’s editions have answers to all the problems, and usually include more elaborate answers. There is often a study guide that has detailed answers to at least some of the problems. The purpose of having the answers to problems in the textbook is not to allow students to cheat, and the answers aren’t usually sufficient to allow cheating (except for multiple-choice problems, which aren’t generally assigned for problem sets anyway). The idea is to allow students to check their work. That way, you can tell if you’re on the right track by checking the answers to the odd-numbered problems. If you understand the material, you should be getting the right answers, and so you’re likely to be getting the right answers on the questions that don’t have answers in the back of the book. If you’re not getting the right answers, then you can ask for help, because of course you have worked on the problem set from the day it was assigned and not waited until the night before it’s due. =) ---
**Author:** ![drewbert](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drewbert/32/15890_2.png) [@drewbert](https://boards.straightdope.com/u/drewbert)\ **Post date:** [November 16, 2004, 3:19am UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/10 "2004-11-16T03:19:27Z")
The one text I ever had like this (in Calculus) had an odd-numbered answer set that was almost totally useless. It made giant leaps over steps, and the final answers were often incorrect. ---
**Author:** ![moriah](https://avatars.discourse-cdn.com/v4/letter/m/b2d939/32.png) [@moriah](https://boards.straightdope.com/u/moriah)\ **Post date:** [November 16, 2004, 4:03am UTC](https://boards.straightdope.com/t/answers-to-odd-numbered-problems/274952/11 "2004-11-16T04:03:02Z")
Could it be that the odd and even problems are paired together such that if you can do one, then you can do the other? This way, in giving you the answer to the odd question, you’d be able to know you can do it, and thus solve the even question. So, if you’re not sure you got #14 right, do number #13 and check the answer in the back of the book, since they’re basically the same problem. Peace.