Xiao Zhang and Xiao Wang jointly process a batch of parts, Xiao Zhang processes 81 parts every day, and Xiao Wang processes 60 parts every day, and the work is completed in 28 days. How many parts are there in total?
小张和小王共同加工一批零件，小张每天加工81个，小王每天加工60个，28天正好完工．这批零件一共有多少个？
<gadget id="calculator">81 + 60</gadget>
<output>141</output>

<gadget id="calculator">141 * 28</gadget>
<output>3_948</output>

<result>3_948</result>