I know that 1/2+1/4+1/8+1/16+... will equal 1
1/2*2 =1
1*2 =2
2+1= 3
if you continue that series, then you get
2+1+1/2+...
2+1+1 =4
Though a more formal way would be something along the lines of
[tex]4=a_0 *\frac{1}{1-r}
[/tex]
pick a random a0, and then just solve for r
