Sven's Official BrainTeaser Thread !! and Sander.

[sputnik]

you start the 7 and 11 minute simultaneously. then when the 7 minute ends, your fifteen minutes begins. four minutes later the eleveln minute will end, then you start it again, and eleven minutes later it ends. voila, 15 minutes

[Sander]

smart sputnik but let me say it this way:
the 15 minutes begin when an hourglass is turned as well

[Mike]

7 and 11 at the same time
turn 7 when it's out, leaving 4 minutes in the second one
when the 4 minutes are done in the big glass, turn the 7 again (has been pouring for 4 minutes, meaning there's 4 minutes remaining when you take it upside down)
when it's done you have
7+4+4=15min

[TW89]

7 and 11 at the same time
turn 7 when it's out, leaving 4 minutes in the second one
when the 4 minutes are done in the big glass, turn the 7 again (has been pouring for 4 minutes, meaning there's 4 minutes remaining when you take it upside down)
when it's done you have
7+4+4=15min

Yup, I just been thinkin bout this one real hard then find you've got answer lol

[Mike]

I'll take the liberty to give you another one

Here goes!

three numbers: a<b<c are put together so that they form every three digit number they can. The sum of all of the three digit numbers is 1554. Which are the numbers?

if a = 4, b = 5, c =6, then they can form 456, 546, etc., etc.

[TW89]

1, 5, 54?

[Mike]

That is wrong.

54? the number has a range from 1-9, or else you can't put them into three digit numbers.

[TW89]

That is wrong.

54? the number has a range from 1-9, or else you can't put them into three digit numbers.

Oh yh didnt really understand that bit, do now though

[a;sdlfkjas;df]

I'll take the liberty to give you another one

Here goes!

three numbers: a<b<c are put together so that they form every three digit number they can. The sum of all of the three digit numbers is 1554. Which are the numbers?

if a = 4, b = 5, c =6, then they can form 456, 546, etc., etc.

1<2<4

[sputnik]

yeh hes right took me like 2 seconds to figure out

[a;sdlfkjas;df]

and to get there:

the number will spend two "combinations" in each position

the hundreds must add to around 1500 (you're looking for small numbers), and the ones should add to something 4

1,2,3 will only give you 1200.  plus a generous avg of 30 per combination.  6*30=180=1380.
1,2,4 will give you 1400.  generous 30*6=180=1400+180=1580.  adding those combinations up = 1554

[Mike]

Nice done :thumbsup:

for a more mathematical solution:

a number abc can be written as 100*a +10*b + c

all combinations added is:

222*a+222*b+222*c=1554

divided by 222 the remnant is

a+b+c=7

where 1+2+4 is the only solution for a<b<c

New riddle:

In a game there are 200 boxes next to eachother (a line, not a circle). Every box has a value of 1 from the beginning.

So in the first round, you add 1 to every box

In the secound round you add 1 to every second box

in round three you add 1 to every third box

and so on.

What number is in box 120 after 200 rounds?