The integer 1 uses 1 number, and the integer 20 uses two numbers 2 and 0. How many numbers are used from the integer 1 to the integer 1000?
整数1用了1个数字，整数20用了2和0两个数字，从整数1到整数1000一共要用多少个数字．
<gadget id="calculator">90 * 2</gadget>
<output>180</output>

<gadget id="calculator">900 * 3</gadget>
<output>2_700</output>

<gadget id="calculator">9 + 180 + 2_700 + 4</gadget>
<output>2_893</output>

<result>2_893</result>