What is the digital sum of $(99...9)^3$?
71789
Prove that the sum of digits of $(999...9)^{3}$ (cube of integer with $n$ digits $9$) is $18n$
30496
Casting nines and elevens in other bases (radix) and doing check sums for binary
131708
Sum of powers of natural numbers
37603
Finding the Integer part of $\sum_{k=2} ^{9999}\frac{1}{\sqrt k}$
63965
How can I compute the sum of $ {m\over\gcd(m,n)}$?
151179
Finding the value of $\sum k/3^k$
83145
Sum of rational numbers
51299
How many digits is $99^{99}$ without a calculator?
147505
Calculate the last digit of $3^{347}$
61047
Find the coefficient of ${x^9}$ in the expansion of $ (1 + x)( 1 + x^2)( 1 + x^3)..(1 + x^{100})$
94060
Sum of square binomial coefficients
111602
Help with telescoping sum $\sum_{i=3}^n \frac{1}{i(i+3)} $
25181
Simple numerical methods for calculating the digits of $\pi$
47706
Find the value of $ \sum_{n=1}^{\infty} \frac{n^3}{3^n} $
126105
Compute $\sum_{k=1}^{n} \frac 1 {k(k + 1)} $
286
Is it true that $0.999999999\ldots=1$?
103545
Prove "casting out nines" of an integer is equivalent to that integer modulo 9