When Xiao Dingding calculated 500-□*10, he made a mistake in the order of operations. He calculated the subtraction first, and the result was 4900. What is the correct number for this question?
小丁丁在计算500-□*10时，把运算顺序弄错了，先算了减，结果得到4900，这道题的正确得数是多少．
<gadget id="calculator">4_900 / 10</gadget>
<output>490</output>

<gadget id="calculator">500 - 490</gadget>
<output>10</output>

<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<gadget id="calculator">500 - 100</gadget>
<output>400</output>

<result>400</result>