1+2+2^2+2^3+2^4+2^5+2^6=？ Choose the most appropriate option
A) (2^3-1)(2^3+1)	B) 2^6+1	C) 2^7-1	D) 2^5+1	E) 2^5-2
From 1+2+2^2+2^3+2^4+2^5+2^6=1(2^7-1)/(2-1)=2^7-1, the correct answer is 2^7-1.
<result>C</result>
1+2+2^2+2^3+2^4+2^5+2^6=？