MathDB
AMC 8 2005 Problem 24

Source:

July 23, 2011

Problem Statement

A certain calculator has only two keys [+1] and [x2]. When you press one of the keys, the calculator automatically displays the result. For instance, if the calculator originally displayed "9" and you pressed [+1], it would display "10." If you then pressed [x2], it would display "20." Starting with the display "1," what is the fewest number of keystrokes you would need to reach "200"?
<spanclass=latexbold>(A)</span> 8<spanclass=latexbold>(B)</span> 9<spanclass=latexbold>(C)</span> 10<spanclass=latexbold>(D)</span> 11<spanclass=latexbold>(E)</span> 12 <span class='latex-bold'>(A)</span>\ 8\qquad<span class='latex-bold'>(B)</span>\ 9\qquad<span class='latex-bold'>(C)</span>\ 10\qquad<span class='latex-bold'>(D)</span>\ 11\qquad<span class='latex-bold'>(E)</span>\ 12