It has been 23 days to build a road with a length of 8,400 meters, with an average of 150 meters per day. How many meters are left unrepaired?
修一条长8400米的路，已经修了23天，平均每天修150米．还剩多少米没有修？
<gadget id="calculator">23 * 150</gadget>
<output>3_450</output>

<gadget id="calculator">8_400 - 3_450</gadget>
<output>4_950</output>

<result>4_950</result>