sum of digit (1 Viewer)

juantheron · May 30, 2012

Let $a_{1},a_{2},a_{3}......,a_{10}$ be a permutation of the set $\left\{1,2,3......,10 \right\}$ such that the sequence $a_{i}$

decreases first and then increases like $8,6,4,1,2,3,5,7,9,10$ . If $N$ is the number

of such permutations,then the sum of digits of $N$ is

Fus Ro Dah · May 30, 2012

From where did you get this question?

Nooblet94 · May 30, 2012

Fus Ro Dah said:
From where did you get this question?

^That. I've always been curious. You post such interesting questions that go far beyond the hsc course. It's intriguing.

barbernator · May 30, 2012

Nooblet94 said:
^That. I've always been curious. You post such interesting questions that go far beyond the hsc course. It's intriguing.

i'm guessing he has studied some form of combinatorics at uni.

RealiseNothing · May 30, 2012

510 permutations, therefore answer is 6?

sum of digit (1 Viewer)

juantheron

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Fus Ro Dah

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Nooblet94

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barbernator

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RealiseNothing

what is that?It is Cowpea

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