How many keystrokes are needed to type numbers from 56 to 200?	Choose the most appropriate option:
A) 310 B) 391 C) 270 D) 289 E) None of these
Explanatory Answer   While typing numbers from 56 to 200, there are 44 two-digit numbers: from 56 to 99.   Each of these numbers requires 2 keystrokes.   Therefore, 88 keystrokes to type the 2-digit numbers.   There are 101 three-digit numbers: from 100 to 200.   Each of these numbers requires 3 keystrokes.   Therefore, 303 keystrokes to type the 3-digit numbers.   Totally, therefore, one requires   88 + 303= 
<gadget id="calculator">  88 + 303</gadget>
<output>391</output>
391 keystrokes.   Choice 391 is the correct answer.
<result>B</result>
How many keystrokes are needed to type numbers from 56 to 200?