Brainy Puzzles
Puzzle Solvers: Interesting brainy puzzles shared by fellow puzzlers
355 Members
Join this group to post and comment.
Kaustubh Katdare • Dec 3, 2013

Quick Puzzle | Time Limit: 30 Seconds

Found this puzzle on LinkedIn and I think it's a good mental exercise. Not at all difficult to crack, but should give you a good 30 seconds π

• 9 = 90
• 8 = 72
• 7 = 56
• 6 = 42
• 3 = ??
If you take more than 30 seconds to crack this, you've gotta be needing some brain exercise. Spend time on CE and keep your brain engaged!
Igneta D'Souza • Dec 3, 2013
12π
Ankita Katdare • Dec 3, 2013
18 it should be. Or is this a problem that has multiple correct answers based on assumptions or not-enough-data.
12
Anoop Kumar • Dec 3, 2013
12 π
x = x*(x+1)
5 = 30
4 = 20.
3 = 12.
2 = 6.
1 = 2.

(or)

6 = 42
3 = 18 Which one is right???
Sandeep Taurean • Dec 6, 2013
12
Shailaja Tiwari • Dec 7, 2013
Kaustubh Katdare
π

• 9 = 90
• 8 = 72
• 7 = 56
• 6 = 42
• 3 = ??
time taken<20sec
ans: 12
Aadit Kapoor • Dec 7, 2013
ans : 18 (time taken 9 seconds)

explanation-:

9 = 90
8 * 9 = 72
7 * 8 = 56
6 * 7 = 42
3 * 6 = 18
Sanyam Khurana • Dec 7, 2013
12..

Took like just 2 sec π
Anoop Kumar • Dec 7, 2013
What is logic for getting 18?
Shailaja Tiwari • Dec 8, 2013
ianoop
What is logic for getting 18?
they must have done by this way :
• 9 = 90
• (8*9=72)
• 8 = 72
• ( 7*8=56)
• 7 = 56
• (6*7=42)
• 6 = 42
• (3*6=18)
• 3 = ??
Anoop Kumar • Dec 8, 2013
Shailaja Tiwari
they must have done by this way :
• 9 = 90
• (8*9=72)
• 8 = 72
• ( 7*8=56)
• 7 = 56
• (6*7=42)
• 6 = 42
• (3*6=18)
• 3 = ??
Really this is logicπ¨ , where did 9=90 came fromβ and why 3 came in series after 6, while other numbers are just x-1.

Why not x = x*(x+1).
Shailaja Tiwari • Dec 9, 2013
9=90 - as 8 is multiplied with its higher consecutive no. 9,similarly they must have added 9 with its higher consecutive no.10.
and don't know about the series problem ,others may not have noticed it
Shailaja Tiwari • Dec 9, 2013
π¨
Ajay Pandey • Dec 9, 2013
Right answer is 18 or 12 depends on ur logic.In objective exams, options must be either 12 or 18 not both.My answer is 12 bcos first match a pattern and then relation between consecutive options.
Anoop Kumar • Dec 9, 2013
Ajay Pandey
Right answer is 18 or 12 depends on ur logic.In objective exams, options must be either 12 or 18 not both.My answer is 12 bcos first match a pattern and then relation between consecutive options.
Still not convinced, how some of us getting 18.
Ajay Pandey • Dec 9, 2013
8*9=72
7*8=56
6*7=42
3*6=18
by wrong logic ......π right answer is 12
sargam shukla • Dec 9, 2013
Kaustubh Katdare
Found this puzzle on LinkedIn and I think it's a good mental exercise. Not at all difficult to crack, but should give you a good 30 seconds π

• 9 = 90
• 8 = 72
• 7 = 56
• 6 = 42
• 3 = ??
If you take more than 30 seconds to crack this, you've gotta be needing some brain exercise. Spend time on CE and keep your brain engaged!
12
Aadit Kapoor • Dec 11, 2013
write a program to print a message without using printf function.
Raj A • Dec 14, 2013
12
12 or 18 based on our assumption....
But i think 12 suits the most....
Took <15 s.....
jeshukb09 • Dec 28, 2013
18
Kaustubh Katdare
Found this puzzle on LinkedIn and I think it's a good mental exercise. Not at all difficult to crack, but should give you a good 30 seconds π

• 9 = 90
• 8 = 72
• 7 = 56
• 6 = 42
• 3 = ??
If you take more than 30 seconds to crack this, you've gotta be needing some brain exercise. Spend time on CE and keep your brain engaged!
it should be 12
vijay jangid • Jan 5, 2014
12
18π
KenJackson • Jan 7, 2014
write a program to print a message without using printf function.
At first I thought you must have posted in the wrong thread. But now I think I see that you think the answer 18 is bad logic, a non sequitur, so you posted your own non sequitur to protest. Right?

BTW. The answer to your puzzle is trivial if using one of the many computer languages that don't have a printf function.
pavani kumari • Aug 31, 2014
Kaustubh Katdare
Found this puzzle on LinkedIn and I think it's a good mental exercise. Not at all difficult to crack, but should give you a good 30 seconds π

• 9 = 90
• 8 = 72
• 7 = 56
• 6 = 42
• 3 = ??
If you take more than 30 seconds to crack this, you've gotta be needing some brain exercise. Spend time on CE and keep your brain engaged!
its 18
Shashank Moghe • Sep 12, 2014
Well 18 (3-4 seconds). Also, if you (want to) intrapolate the series, the answer comes to 12. There seems to be a confusion as to which one is correct.

If it were up to me , I would justify 18 as the correct answer because of the way the question is presented. I was not "told to" intrapolate.
18!!! π
ManojKiran Eda • Sep 19, 2014
12
Satheesh S.S • May 6, 2015
a*(a+1) so 12