How many keystrokes are needed to type numbers from 1 to 500? Choose the correct choice from the following answers.
A) 1750
B) 1000
C) 1500
D) 1529
E) 1392
Explanatory Answer   While typing numbers from 1 to 500, 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 401 three-digit numbers: from 100 to 500.   Each of these numbers requires 3 keystrokes.   Therefore, 1203 keystrokes to type the 3-digit numbers.   Totally, therefore, one requires   9 + 180 + 1203= 
<gadget id="calculator">  9 + 180 + 1203</gadget>
<output>1_392</output>
1392 keystrokes.   Choice 1392 is the correct answer.
<result>E</result>
How many keystrokes are needed to type numbers from 1 to 500?