When the little sloppy was doing a subtraction problem, he regarded the 0 in the ones place of the subtrahend as 6, and the 4 in the tens place as 9, and the result was 661. What should be the correct result?
小马虎在做一道减法题时，把被减数个位上的0看成了6，把十位上的4看成了9，结果得661，正确的结果应该是多少．
<gadget id="calculator">90 - 40</gadget>
<output>50</output>

<gadget id="calculator">6 - 0</gadget>
<output>6</output>

<gadget id="calculator">50 + 6</gadget>
<output>56</output>

<gadget id="calculator">661 - 56</gadget>
<output>605</output>

<result>605</result>