How many terms are there in 2, 4, 8, 16,..., 512? Options:
A) 14 B) 11 C) 12 D) 9 E) 8
2, 4, 8, 16, ..., 512 is a G.P with a =2   and r =4/2= 
<gadget id="calculator">4/2</gadget>
<output>2</output>
2   Let the number of terms be n. Then   2 x 2 ^n-1= 512   or 2^n-1 = 256 = 2^8   Thus n - 1 =8   n= 9   ANSWER:9
<result>D</result>
How many terms are there in 2, 4, 8, 16,..., 512?