What is the following value when expressed as a common fraction:
1/2 + 1/2^2 + 1/2^3 + ... + 1/2^8 + 1/2^9 + 1/2^10 + 1/2^11 + 1/2^12
sumfor(n, 1, 12, 1/(2^n))==4095 / 4096
