Brain Teasers
The Combination For $1,000,000
Recently, Brainiac, the extremely rich father of Brainiac Jr. had passed away. He had left one million dollars to Brainiac Jr.
However, the money was locked in a safe, and Brainiac Jr. would not get the money unless he knew the combination. Brainiac, being the brainiac that he is, left a number series for his son to work out. If he could not figure it out, he wouldn't get anything.
The combination is a 3-digit number, and to stop him randomly guessing he would only be able to try once every day.
Here is the series:
3, 11, 31, 55, 91, ...
Brainiac Jr. managed to finish the series, and get the million dollars. Can you?
However, the money was locked in a safe, and Brainiac Jr. would not get the money unless he knew the combination. Brainiac, being the brainiac that he is, left a number series for his son to work out. If he could not figure it out, he wouldn't get anything.
The combination is a 3-digit number, and to stop him randomly guessing he would only be able to try once every day.
Here is the series:
3, 11, 31, 55, 91, ...
Brainiac Jr. managed to finish the series, and get the million dollars. Can you?
Hint
It might make more sense if I change it to 2, 12, 30, 56, 90, ...Answer
The final number is 131.The series works from:
1 * 2 = 2 ( + 1 = 3 )
3 * 4 = 12 ( - 1 = 11 )
5 * 6 = 30 ( + 1 = 31 )
7 * 8 = 56 ( - 1 = 55 )
9 * 10 = 90 ( + 1 = 91 )
11 * 12 = 132 ( - 1 = 131 )
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Comments
Oh man, I'm not $1 mill richer today... bummer! I love these logical, common sense teasers, but I just could not get this one.
Thanks for a really great tease! I worked on it off and on all day!
Thanks for a really great tease! I worked on it off and on all day!
Me too, not richer I mean. Great job, but now I have a headache. Anybody float me a loan for some asprin? More please? I mean more teasers!
Or, just try everyday anyways. It would take less than 3 years to get it in any event, averaging about 1.5 years. But yeah, it would take a lot less than 1.5 years to figure out the series so....yeah :]
Ugh, got the 132 (after the hint) but forgot to subtract 1.
I did it by 2+ 10 = 12
12 + 10 + 8 = 30
30 + 10 + 8 + 8 = 56
56 + 10 + 8 + 8 + 8 = 90
90 + 10 + 8 + 8 + 8 + 8 = 132
I did it by 2+ 10 = 12
12 + 10 + 8 = 30
30 + 10 + 8 + 8 = 56
56 + 10 + 8 + 8 + 8 = 90
90 + 10 + 8 + 8 + 8 + 8 = 132
There is an alternative answer:
3,11,31,55,91...
When we subtract each left number with it's right neighbour, we get: 4, 20, 24, 44
In which we get the next number by adding the previous two, thus the next number in this serie is 68. So the answer is 179:
68+91=179
3,11,31,55,91...
When we subtract each left number with it's right neighbour, we get: 4, 20, 24, 44
In which we get the next number by adding the previous two, thus the next number in this serie is 68. So the answer is 179:
68+91=179
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