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Bob's Party

Trick brain teasers appear difficult at first, but they have a trick that makes them really easy.


Puzzle ID:#33639
Fun:*** (3.04)
Difficulty:* (0.94)
Submitted By:BatteryAen*****!




Bob was having a big party. He decided on a technique to get lots of people to come. He invited his five closest friends and said that they could each invite 4 people.

Each of those could invite 3.
Each of those could invite 2.
Each of those could invite 1.

Overall, how many people did Bob invite to his party?

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Oct 25, 2006

Note to self "Read the category before doing complex calculations"
I confess to being tricked. Good one.
Oct 25, 2006

I did a quick calculation, but when I read the last line, I thought "What category is this?"
Oct 25, 2006

finally, a decent trick teaser! thankyou.
Oct 26, 2006

good one
I did all the complex calculations then when i had the answer i re read the Question again and though SILLY!!! Must always read Question before doing calculations LOL
Thanks for the Puzzle
Oct 26, 2006

I like it, lol.
Oct 26, 2006

I think too much I kept trying to add up all of the people
Oct 26, 2006

Yes! I got it!
Oct 26, 2006

Like it!I was about to add up all the people then I was like Duh! nd I got the answer!
Oct 28, 2006

I was about to open up the calculator on my computer then realised.
Oct 29, 2006

I got it first try. Very good teaser. I enjoyed it a lot.
Oct 29, 2006

Kits, cats, sacks and wives,
How many were going to St. Ives? This one has whiskers!
Oct 30, 2006

i got it right!!!
at first i was like "well... 5 then 4 each" then i'm like "WAIT" and then got it. yey!!!
Oct 30, 2006

I dont get it! could someone maybe explain? but it must of been a good teaser if everybody else got it!
Oct 30, 2006

oh! now I get it! bon only invited 5 people! his friends invited the rest!
Nov 01, 2006

Good trick - I got it though.
Nov 02, 2006

Wow I feel so stupid.
Nov 07, 2006

Just remember the category! Way to go! I thoroughly enjoyed it! A teaser which fits the category it was made for! Keep them coming!
Nov 08, 2006

thats a good one at first i was adding all the people up when the answer was right there in front of me
Nov 10, 2006

i did all the calculations in my head, didn't take to long
then when i saw the answer, i was just like huh?
and then i reread it and got it
Nov 18, 2006

i was tricked..... but then again im always tricked so it's all good
Nov 22, 2006

Nov 23, 2006

thanks everyone for all your comments
Nov 24, 2006

Great teaser! I got it on my first try. Thought of the category and the answer just came into my mind.
Nov 26, 2006

I almost got tricked, but, like Boodler, I read the category first.
Nov 26, 2006

Nov 26, 2006

Great Attempt to Trick someone into calculations; question was simple; answer was obvious; but I did start to calculate and then re-read and got it right away. lmurray, why are you such a kill-joy? Is that your lot in life????????
WHAT DID YOU SAY? i thought so! this is fun for us all! Happiness comes from within; I choose to be happy and bring happiness and encouragement to others.
Nov 26, 2006

I know one who would not get invited...

A good but a bit sneaky, just as a teaser should be.
Nov 26, 2006

You got me! Good new one based on an old teaser.
Nov 26, 2006

Very good. I did the calcalateions and got 96.I didn't get it.
Nov 26, 2006

that was a good one keep it up ......
Nov 26, 2006

Okay, I too did the calculations without reading the category first. I came up with 45 people coming to Bob's party. Someone else came up with 96. So, how many besides Bob were at the party?
Nov 26, 2006

2 letters-

Nov 26, 2006

Of course it was easy, the hard part was to read carefully and not get tricked!
Nov 26, 2006

It was great though u should have not put the word "overall" that word means everyone so yea but it was a really really good one I liked it!!!
Nov 26, 2006

who likes wresling? i do DX is the best!!!
Nov 26, 2006

You tricked me, and I thought I was so clever...NOT! Color me red.
Nov 26, 2006

i need to stop thinking
Nov 26, 2006

Technically, Bob did set the maximum number of invited guests to his party. The trick is a failure by using the word "Overall", because overall Bob did give invitation instructions for a total group:

5+(5x3)=20 sub total first group
20+((20-5)x2)= 80 sub total for next group
80+((80-20)x1)=140 total guests

Perhaps if the question were phrased as; How many friends did Bob directly invite?
Nov 26, 2006

i calculated , was very proud of myself for coming up with an answer , then i clicked the answer button . Loved this one, I'm kinda new at this, so now i know I'm supposed to check the catagory. very good one
Nov 26, 2006

great teaser!!!!!!! I loved it!!!
Nov 26, 2006

I even realized that it was a trick teaser and still fell for it! I think I need to have someone check to see if my mind is malfunctioning! Anyway, Great Teaser!
Nov 26, 2006

Great teaser, I got it right! and right away
Nov 26, 2006

okay misterfish.
a) TECHNICALLY bob only did invite 5 people. it was his friends and their friends ect. that invited the rest.

b) if your going to be all technical with your calculations, how about at least being correct, yeah? because if the trick HAD been the calculations you would have fallen for it. you dont multiply the last group by one because they all invited ONE MORE PERSON. so if you did. you would be left with the same number as you had. duh.

c) if the question were re-phrased as "how many friends did bob DIRECTLY invite?" it wouldnt be a TRICK. would it?
Nov 26, 2006

Okay. You got me too. This was a really fun, tricky teaser. I liked it.I did all the calculations and read the answer confident I got it correct. You got me!!
Nov 26, 2006

That was a good one, I figured out without doing all the calculations.
Nov 26, 2006

I am glad I didn't fall for the trick... even those who did, u got some exercise on the other side of the brain, didn't ya? for those who did take the pains to calculate the total number of invited people "overall", what do we agree to be the total overall?

5+ (5*4) + (5*4*3) + (5*4*3*2) + (5*4*3*2*1) = 325

any takers?
Nov 26, 2006

"Overall" I got 120; is there an mathematics professor out there who could give us the real scoop?

Dropping that one initial word would have been a fairer way to ask the question and still qualify as 'trick'.

Now as I continue my trip to St. Ives....

Excuse me: A or any ... professor
Nov 26, 2006

tht was good at first i was gonna calculate all the numbers then it said category "trick" and i still didnt get but now i understand awsesome riddle!
Nov 26, 2006

What can I say,Ya got me GOOD TRICKY
Nov 26, 2006

omg;..i got 48 gests....NO IDEA WHAT I DID it shudve been directly invited...coz otherwise...some can figure out the answer and actually get it right....

Nov 26, 2006

The original 5 could each invite 4, so 5 times 4 = 20 +the original 5 =25, those 25 could invite 3 each, 75 + the 25=100. Those 100 could each invite 2 so 200 + the 100 =300. each of the 300 could invite 1, so 300 + 300 = 600. Yes? No? Anyways, that's the answer I got.
Nov 26, 2006

lmfao.. i was about to start figuring it out and then i rembered that it was trick.. then i got the answer
that was a good one
Nov 26, 2006

I go the answer right away, but being the person I am I decided to see how many people came (besides bob). first there's the 5 friend each invited 4 (25), but then only 20 could invite more friends. so it came out to (325)

5+ (5*4) + (5*4*3) + (5*4*3*2) + (5*4*3*2*1) = 325 (which is what -tpkarth- got and seems to be correct
Nov 26, 2006

You got me
Nov 26, 2006

OK, so I did the math, then reread the question and came up with the right answer.
But the math I did, gave me the same answer as Brandon182001, which is 600, using the same method as he did.
Nov 26, 2006


Technically I did miss part of the question (I was still fairly incoherent) the first time through which was the 5 inviting 4, however, if you understand the way brackets work, what I have shown is correct. BTW: I see you conveniently ignored the word "overall". Bob, being a host, offered the total number of invitations.

5+(5x4)=25 sub total first group of the close friends inviting 4 people each.
25+((25-5)x3)= 85 sub total for next group minus the ineligible first group
85+((85-25)x2)=205 sub total for next group minus the ineligible first and second group
205+((205-85)x1)=325 total guests

Main Entry: 1over•all
Pronunciation: "O-v&r-'ol
Function: adverb
1 : ALL OVER 1
2 : from one end to the other
3 a : in view of all the circumstances or conditions b : as a whole : GENERALLY c : with everyone or everything taken into account
(user deleted)
Nov 26, 2006

brandon and victor, when you multiply the second group by 3, you have to exclude the first 5, because they each already invited 4 and can not invite any more, so you would multiply 3 by 20, not by 25. so the answer would be 325.
also i agree that by saying overall it includes all the people invited, not just the 5
(user deleted)
Nov 26, 2006

actually i just thought of something. the answer, instead of being 325, would be impossible to calculate, because just because someone could invite 3 or 4 more people, doesn't mean they will. some people may not invite anyone, so it is impossible to know how many people total were invited with the information given.

but, assuming each person invites the maximum number of people they can invite, then the correct answer would be 325.
Nov 26, 2006

at first, i thought it was silly to post comments about these teasers. but now i see that its fun. its kinda like a little community. im definately warming up to it. i liked this one a lot. instead of equations, i did a diagram. funny stuff.
Nov 26, 2006

Nov 27, 2006

This was a great teaser. I was on the step that lead me to the answer I originally got, 325, when i went omg!!! this is a trick isnt it?!?!
I thought it was great
Nov 27, 2006

Cool! Several people got "the maximum number of guests at the party"=325, but what about the general expression? What if the host invited 7 that can invite 6 that can invite 5...? What if he doesn't want more than 3 degrees of separation to him (a friend of a friend of a friend)?
If n is the initial number of friends (1 degree of separation, n=5 in the original riddle), and d is the maximum degree of separation (d=5), then the people at the party is


How will be the general expression if d is the maximum degree of separation between ANY person at the party?? :-)
Nov 27, 2006

I guess I should have read the category!
Nov 27, 2006

Well, someone summoned a professor so I had to answer.
First and foremost, I was at the party and it was "off the heezy!!"
Secondly, this teaser was cool. Of course I got it off the bat because of the category. Rule#1: knowing the category is 75% of the work
Thirdly, there are some people with some serious math issues, to name a few – synlapse and Victor! Misterfish – though you got it right later your initial answer troubled me. qwertyopiusa – you suffer from too much free time, your math is actually accurate but your thought process is well...
However, the closest answer was provided by D-Love – after a moment of introspection he pontificated that the answer cannot be accurately provided with this amount of information. Surely we must make room for real life answers and real life situations, however that is what ln(e) is for – natural log with base e provides insight into real life numbers that we encounter in everyday life or in mathematical terms - expressions in which the unknown variable appears as the exponent of e occur much more often than exponents of 10 (common log) or in this case 5 (number of invites)
E has been defined as 2.718281828459... so by using this number as our base we could come closer to a more accurate number but we must remember there are no exacts in mathematics as with all sciences (for those confused because math and science were taught in two different rooms in your elementary school, math is a type of science as science is a broad field that involves computational, quantitative, and qualitative analysis...
That being the case we can fairly assume that of the potential 325 invitees, 130.4...were actually invited.
Which is crazy because I was at the party and it was packed to the brim. I had honeys to my left and honeys to my right.
Rule #2 Always invite me to your party b/c Ladies love the professor...
Nov 27, 2006

oH man! My whole comment disappeared! Well, Ima say it shorter: Just because it says: "overall" does not change the fact that the teaser states that Bob invited five blah blah. You could say "how many were invited overall", and that would mean the total of all invitees, but bob only invited five people overall or underall.
Nov 28, 2006

overall bob invited 5 people in their underalls?
Nov 29, 2006

I thought it was well thought out and if you didnt understand it, you wont get it.
Nov 29, 2006

Nov 30, 2006

I GOT it. I thought it was all the adding until I read the category and then I realized he only DIRECTLY invited 5.
Nov 30, 2006

Good thing this site has categories cuz that was the biggest hint!! Never would have gotten it without realizing it was in the trick category!!
Nov 30, 2006

My oh my so much to do over one little word "Overall". Trick was the word of the hour! And it was a good trick. More please.
Dec 02, 2006

omg i worked at this for like 10 minutes and did sooo much work!!! i got an answer of 300 and i was sure of it...BUT THEN I LOOKED ATT THE ANSWER!!! anywayz good TRICK teaser!!
Dec 02, 2006

omg i worked at this for like 10 minutes and did sooo much work!!! i got an answer of 300 and i was sure of it...BUT THEN I LOOKED ATT THE ANSWER!!! anywayz good TRICK teaser!!
Dec 12, 2006

A good trick. I'm glad that so many have calculated the answer (to the question that wasn't asked) as 325. I originally came up with 325, but having seen someone else come up with 140 I didn't have the confidence to contradict them. I was sure they were wrong, but it would have been a bit embarrassing to say so and give an equally wrong answer.
Dec 12, 2006

Wonderful! This is a textbook example of what a "Trick" teaser should be! AND -- the best part -- I wasn't tricked!! Not for a second!!!!

jacstop, oh my my my. Such lovely mathematical ribbons wrapped around the best present of all -- humour!! Thanks so much for that!!! I think ln(e) was the dead giveaway of your BS though ....though truly, that's not "1" that many will understand!
Dec 14, 2006

If everyone Bob had directly invited invited as many people as they were allowed, there would be 480 people at Bob's rather large party.
Dec 14, 2006

Oops! Forgot the original 5!
485 if they all came
Dec 19, 2006

omg, nice one, you tricked me with the saying. probaly one of the best tricks here!

Dec 25, 2006

i got that one. BOB invited five, but HIS FRIENDS invited more.
Jan 01, 2007

ugh i am so stupid i sat there and added up everything to figure it out!!!
Jan 08, 2007

I got it! I got it! *jumps*
Feb 02, 2007

i accually got this one!!! yay!!!!! go me!!!!!!!!!!!
Feb 10, 2007

I'm so glad I looked at the category before trying to solve the puzzle.
Feb 16, 2007

Nice teaser, I got it as soon as I read the category

Just a question...why is everyone arguing about the math of the problem when none was even involved??? The editors wouldn't have let it through if they didn't think it made sense, and there's no point in arguing about the math in this problem that doesn't exist.
(user deleted)
Feb 23, 2007

Apparently I just woke up and didn't pay enough attention in class. LOL. Very funny.
Feb 26, 2007

Yeah, A nice teaser and yes I got it.
Feb 27, 2007

lol....eeeaaaassssyyy =}
Mar 05, 2007

Mar 18, 2007

Loved it! Really I think that you need to look at that category though! If you think it's going to be a trick then you realize whats going on!
Mar 23, 2007

You should have asked what color his eyes were....
May 04, 2007

nice one you got me
May 15, 2007

Darn, Darn, Darn it all to hec! My brain hurts and now I feel really really stupid. I hate math problems. I wish I'd had enough sense to know this wasn't one.
May 16, 2007

lol i did all the math out and just before i clicked the answer button i realized that he only invited 5 people himself
Jun 06, 2007

I added them all up and got 325, and I thought that I figured it out but I guess I was wrong. Good one!
Jun 25, 2007

I liked this one. It definetly tricked me Very nice job
Jul 03, 2007

I thought 5 factorial was the answer!!!
Jul 22, 2007

I worked all of that out then at the end when i worked it all out i thought: "Isnt it just 5?"
So I clicked on the answer and I felt silly! I got it b4 i clicked on the answer thoguh!
Oct 03, 2007

Oct 04, 2007

Okay, here's what I think. Bob invited 5 people to the party. Each of those 5 invited 4, so 5x4=20. Each of those 20 invited 3, so 20x3=60. Each of those 60 invited 2, so 60x2=120. Each of those 120 invited 1, so 120x1=120. So the total would be 5+20+60+120+120=325. So the number of people INVITED to the party (assuming no duplicates) is 325. The number of people AT the party (assuming everyone came) is 326. The number BOB invited is 5.
Oct 18, 2007

You mean hos many did bob DIRECTLY invite. He indirectly (using his friends as proxies) invited everyone else.
Apr 04, 2008

*giggle* I got at first try. Remember people, we're in Trick here.
Aug 18, 2008

Wow. I must admit, I got tricked pretty good. Better read the category correctly next time..

Oh, yeah, to the people doing the calculations for the overall party count, you are TOTALLY wrong!!!!

This is correct:

Bob invites 5 to his party. With Bob himself, this includes 6 guests. Now, if each of his 5 friends invite 4 each, that equals 20 additional guests, equaling 26 if added to 6. Then, from 26, his 4 friend's friends invite 3 each, equaling 12 MORE people. 12 + 26 = 38. THEN, his three friend's friend's friends invite two more each, totaling 6, which, added to 38, equals 44. Finally, his two friend's friend's friend's friends invite one EACH, equaling two more. 44 + 2 = 46.

In all, 46 attend the party.

To the guys who calculated before, you were wrong because you factored in Bob's friends every time during the multiplication. If that was true, Bob's friends must clone a lot, eh?
Sep 08, 2008

This was easy, but I was reading the comment before me and have some problems with it:

Bob invites 5 to his party. With Bob himself, this includes 6 guests. Now, if each of his 5 friends invite 4 each, that equals 20 additional guests, equaling 26 if added to 6.

--Correction Below--
These 20 additional friends invite 3 each, equaling 60 MORE people. 60 + 26 = 86. THEN, his 60 friend's friend's friends invite two more each, totaling 120, which, added to 86, equals 206. Finally, his 120 friend's friend's friend's friends invite one EACH, equaling 120 more. 206 + 120 = 326.

In all, 326 attend the party (no clones involved).
Nov 08, 2008

yeah i waz bout 2 ad up everything den i waz lyk w8 no can...
Oct 20, 2009

Could you guys please stop showing off by trying to calculate the answer. It was a trick okay? remember... TRICK. lol.
Oct 20, 2009

Could you guys please stop showing off by trying to calculate the answer. It was a trick okay? remember... TRICK. lol.
Nov 26, 2009

I didn't check the category before answering . But here's how I calculated it:
5+5*4+5*4*3+5*4*3*2+5*4*3*2*1 = 5+20+60+120+120 = 325.

That is: he invited 5 people and those invited 5*4 and those invited (5*4)*3 [their number * the number of guests each invited] ...etc.
Nov 26, 2009

Oh that was just plain mean!
Before my morning coffee too!
Here I am calculating this in my feeble mind I get it all figured it out, breezed to the answer and......
Nov 26, 2009

That was HARD. I thought 40. Because, Bob invited 5 friends. And they invited 4 freinds which makes it 20 because 5 X 4 = 20. And so on. You should makes MORE of these tricky teasers!
Nov 26, 2009

I've seen too many of these ,so it was easy for me. Happy Thanksgiving to all.
Nov 26, 2009

The trick category thing gave it away
Nov 26, 2009

Nov 26, 2009

It's not a good trick because if you invite people and tell them they could invite a certain number of people, you ARE inviting them all as well.
Nov 26, 2009

Good one, but pretty tricky..
Nov 26, 2009

AAAAAAAAAAGGGGGGGGGGHHHHHH!!!!!!!! so easy, it was SUPER HARD! great teaser, though. i ended up adding and multipying and got 240! i am so dumb. heheheheheheheheeeee!
Dec 03, 2009

lol. it took me a few seconds and i thought it was five ofcourse
Feb 19, 2010

Got it!
Mar 26, 2010

Kehheh, easy, took a few seconds though. Good teaser!
Jul 22, 2010

Maybe people don't get it: Bob isn't a guest. He's the host!

005 = 1st generation (1*5)
020 = 2nd generation (5*4)
060 = 3rd generation (20*3)
120 = 4th generation (60*2)
120 = 5th generation (120*1)

Total, 325 guests attended the party.

But Bob did only invite 5 people. I'm not going against that.
Nov 26, 2012

You did not trick me. I read the question correctly and seen that it was going to be a tricky answer. so yes, I said 5. Yeah me!
Nov 26, 2012

Easy as pie. But it is still a good trick teaser.
Nov 26, 2012

As with some others, I started to calculate then thought I should check the category. Got it right away after I realized it was a trick.
Nov 26, 2012

Just reading the teaser made this very very ez.
Nov 26, 2012

I love these and having done many like this one, I got it right away. Thanks for a good one! ;)
Nov 26, 2012

Nov 26, 2012

I did the calculations as I read through the teaser (the number of people invited was 325 - racoonieboy demonstrates it well) - then I read the actual teaser question and slapped myself on the forehead! - but I got it right! - Actually, as I was reading through it, I kept expecting the teaser to ask "how many people attended?" which would be impossible to know!
Nice teaser!!
Nov 26, 2012

good one. pays to check out the category doesn't it?
Nov 26, 2015

Yeah that was easy cause at first i thought, what do those things like "each invites 3 each invites 2 each invites 1" but then i realized that bob invited 5 people, and HE wasn't the one to invite the other people!

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