just a simple sum

can anyone explain me the geometric series part in "just a simple sum " tutorial…


that is how to get mod(p^k) value for the geometric sum in all different cases…
can anyone suggest alternative approaches for this problem…

p^k%m can be computed fast by fast modular exponentiation.

please let us know if this wikipedia page is not enough for you to understand.

thanks for the reply…
i can understand that one
but please explain me the part which is under the sideheading (back to geometric series ) in just a simple sum tutorial
or see this link

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