There are 6,450 exercise books in the stationery store, 1,354 were sold in the morning, and 646 were sold in the afternoon. How many copies are left? (calculate in two ways)
文具店练习本6450本，上午卖出1354本，下午卖出646本，还剩多少本？(用两种方法算)
<gadget id="calculator">6_450 - 1_354 - 646</gadget>
<output>4_450</output>

<result>4_450</result>