Sums with an infinite number of summands

  1. \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{2^{n}}+...=?\)
  2. \(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+...+\frac{1}{3^{n}}+...=?\)
  3. \(\frac{1}{4}+\frac{1}{16}+\frac{1}{64}+...+\frac{1}{4^{n}}+...=?\)
  4. \(1+2\left(\frac{1}{2}\right)+3\left(\frac{1}{4}\right)+4\left(\frac{1}{8}\right)+...+n\left(\frac{1}{2^{n-1}}\right)+...=?\)
  5. \(\left(\frac{1}{2}\right)+2\left(\frac{1}{6}\right)+3\left(\frac{1}{24}\right)+4\left(\frac{1}{120}\right)+...+n\left(\frac{1}{(n+1)!}\right)+...=?\)