The electricity consumption displayed by the electric meter of Xinhua Primary School is 61111. If four of the five digits displayed on the electric meter are the same, how many kWh should the school use at least.
新华小学的电表显示的用电量是61111，要使电表显示的用电量的五位数中有四个数码相同，学校至少再用多少度．
<gadget id="calculator">61_666 - 61_111</gadget>
<output>555</output>

<result>555</result>