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How to compute a sum

How to compute a sum

Postby subito » Thu Oct 13, 2011 1:28 pm
Hello,

I'm trying to compute the following Sum:

sum from k = 0 to 30 of [(10^k*(Quotient[199981+8*10^k+1,10^(k+1)]) + Quotient[Min[2*10^k-1,199981%(10^(k+1))],10^k]*(199981%(10^k)+1))]

but wolframalpha doesn't understand my input

i'd also like to solve the equation:

find n (all the n's) such that
(sum from k = 0 to 30 of [(10^k*(Quotient[n+8*10^k+1,10^(k+1)]) + Quotient[Min[2*10^k-n%(10^(k+1))],10^k]*(n%(10^k)+1))])== n

can wolframalpha do that?

Thank you for your help
subito
 
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Re: How to compute a sum

Postby briangilbert » Wed Oct 19, 2011 10:00 am
[quote="subito"]Hello,

I'm trying to compute the following Sum:

sum from k = 0 to 30 of [(10^k*(Quotient[199981+8*10^k+1,10^(k+1)]) + Quotient[Min[2*10^k-1,199981%(10^(k+1))],10^k]*(199981%(10^k)+1))]

but wolframalpha doesn't understand my input

I suggest you try solving each individual computation in the structure to identify the one or ones that are giving trouble. You will probably then be able to see what is wrong.

For instance uif your query was
((1+3) + (5*7)


You would submit the queries:-
1+3
5*7
and then
4*35

Yours will be a little harder to break down.

I suggest you also change the format of the sub questions to maqtch the Input Interpretation in the output.

If it still fails then submit the simplest part that fails and use the Feedback facility at the bottom of the output to report it to the WA Team
briangilbert
 
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