A box of apples weighs 21 kilograms, and a box of pears weighs 15 kilograms. Uncle Li bought 12 boxes of each of the two types of fruit. How many kilograms of fruit did he buy in total?
一箱苹果21千克，一箱梨15千克，李叔叔两种水果各买了12箱，他一共买了多少千克水果？
<gadget id="calculator">21 * 12</gadget>
<output>252</output>

<gadget id="calculator">15 * 12</gadget>
<output>180</output>

<gadget id="calculator">252 + 180</gadget>
<output>432</output>

<result>432</result>