Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

I want to perform $\sum_{i=1}^k \lfloor{\frac{N}{2^i}}\rfloor7^{i-1} $. Is there any technique which performs it?


share|improve this question
Actually, now that I think about it, the edit does not make much sense since the powers of $2's$ cancel to give $\lfloor N/2 \rfloor$. Can the OP please clarify? Thanks. –  Sandeep Silwal Apr 14 '14 at 5:01
Note that the powers of 2 almost cancel out against each other. –  Marc Apr 14 '14 at 5:03
What is $N$? Integer, real? If $N$ is an integer, it is helpful to write $N = 2^ab$ with $b$ odd. –  Sandeep Silwal Apr 14 '14 at 7:18
Yea N is an even integer! –  user1234 Apr 14 '14 at 11:19

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.