Sum of the digits of the sum of the digits of the sum of the digits of $4444^{4444}$?
853
Write down the sum of sum of  sum of digits of $4444^{4444}$
5037
Find the last two digits of $3^{45}$
63965
How can I compute the sum of $ {m\over\gcd(m,n)}$?
41563
Prove that if the sum of digits of a number is divisible by 3, so is the number itself.
26607
The idea behind the sum of powers of 2
11447
How many $4$ digit even numbers have all $4$ digits distinct?
3864
How to find length of digits in an integer?
87163
Error computing sum of sum of digits
56974
Determining the missing digits of $15! \equiv 1\square0767436\square000$ without actually calculating the factorial
28957
Verifying that $2^{44}-1$ is divisible by $89$
28027
Find $\sum_{k=0}^{n}4^k \binom{n}{k}$
12760
The last 2 digits of $7^{7^{7^7}}$
142151
Find the last two digits of $9^{{9}^{9}}$
151179
Finding the value of $\sum k/3^k$
48446
Summation involving a factorial: $1 + \sum_{j=1}^{n} j!j$
99453
Sum of $k$-th powers
101017
What is the sum of $\sum\limits_{i=1}^{n}ip^i$?