How many keystrokes are needed to type numbers from 1 to 200?
Choose one: A) 400 B) 500 C) 492 D) 200 E) None of these
Explanatory Answer   While typing numbers from 1 to 200, there are 9 single digit numbers: from 1 to 9.   Each of these numbers requires one keystroke.   That is 9 key strokes.   There are 90 two-digit numbers: from 10 to 99.   Each of these numbers requires 2 keystrokes.   Therefore, 180 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   9 + 180 + 303= 
<gadget id="calculator">  9 + 180 + 303</gadget>
<output>492</output>
492 keystrokes.   492hoice 492 is the correct answer.
<result>C</result>
How many keystrokes are needed to type numbers from 1 to 200?