Next Number | 5 Sep 2009

Discussion in '\$1 Daily Competition' started by Kshiteej, Sep 5, 2009.

1. KshiteejNew Member

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Which is the next number in below series.

1, 2, 7, 12, 19, 42, ?

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Looks like we would have OP as winner.

3. xpi0t0sMentor

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Nothing found here:
http://www.research.att.com/~njas/s...19,42&sort=0&fmt=0&language=english&go=Search

Without commas this returns 432 pages of results; looked through the first few but there was nothing obvious.

So we need more terms to deduce the sequence.

Of course, any number can be the answer, for example 99, because these are the roots of the equation
x^7-182*x^6+10500*x^5-252586*x^4+2762303*x^3-13306896*x^2+24059196*x-13272336

4. SaswatPadhi~ Б0ЯИ Τ0 С0δЭ ~

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Even I searched there, in vain

Yeah, but then how do we express the general term, say 'n'th term of the series ?? :undecided
As you already said, we probably need some more terms ... :thinking:

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Kshiteej can we have the answer of this so we can have the question for today.

6. xpi0t0sMentor

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Assuming that is enough to deduce the series, then using the same technique as before I get 113.
Code:
1
2	1
7	5	4
12	5	0	-4
19	7	2	2	6
42	23	16	14	12	6

113	71	48	32	18	6

7. Seema786New Member

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that was nice xpi0t0s

8. neo_viNew Member

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The next number is 37. Am i right?

9. KshiteejNew Member

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Hi all,
Consider alternative terms set 2 ie 2,12,42
12-2 = 10 = (2)^3 + 2
42-12 = 30 = (3)^3 + 3

Consider alternative terms set 1 ie. 1,7,19
7-1 = 6 = (2)^2 + 2
19-7= 12 = (3)^2 + 3

as the next number belongs to alternative set 1 ( because next numbers postion is odd)

next number should be 19 + (4)^2 + 4 = 39

10. neo_viNew Member

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I too thought in the same angle. But some thing went wrong

1, 2, 7, 12, 19, 42

The diff b/w 1st and third is 6 (7-1)

The diff b/w 5th and 3rd is 12 (19-7)

So,The diff b/w 7th and 5th should be 18 (37-19) which follows multiples of 6.

Similarly,
the diff b/w 4th and 2nd is 10 (12-2)

the diff b/w 6th and 4th is 30 (42-12)

11. naimishNew Member

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Grrrrrrrrrrrrrrrrrr I hate mathematics :embarasse

12. KshiteejNew Member

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Your logic would be correct if the 6th number is 32 instead of 42 so that the diff b/w 6th and 4th is 20 (32-12) i.e then 2nd difference series will be 10,20,30 like first difference series 6,12,18.

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