How many keystrokes are needed to type numbers from 1 to 1000? Choose the correct choice from the following answers: A) 3001 B) 3001 C) 2704 D) 2890 E) None of these
Explanatory Answer   While typing numbers from 1 to 1000, 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 900 three-digit numbers: from 100 to 999.   Each of these numbers requires 3 keystrokes.   Therefore, 2700 keystrokes to type the 3-digit numbers.   1000 is a four-digit number which requires 4 keystrokes.   Totally, therefore, one requires   9 + 180 + 2700 + 4= 
<gadget id="calculator">  9 + 180 + 2700 + 4</gadget>
<output>2_893</output>
2893 keystrokes.   Choice 3001 is the correct answer.
<result>B</result>
How many keystrokes are needed to type numbers from 1 to 1000?