Write from 0, 1, 2, ... to 1000000 in turn, then what is the sum of all the digits of these numbers.
从0，1，2，…依次一直写到1000000，那么这些数的所有数码的和是多少．
<gadget id="calculator">9 * 6</gadget>
<output>54</output>

<gadget id="calculator">54 * 500_000</gadget>
<output>27_000_000</output>

<gadget id="calculator">27_000_000 + 1</gadget>
<output>27_000_001</output>

<result>27_000_001</result>