Two groups collected leaf specimens. The first group consisted of 20 people, each of whom collected 15 leaves, and the second group of 18 people, each of whom collected 19 leaves. How many slices did the two groups collect in total?
两个小组采集树叶标本，第一小组20人，每人采集15片，第二小组18人，每人采集19片．两个小组一共采集多少片？
<gadget id="calculator">15 * 20</gadget>
<output>300</output>

<gadget id="calculator">19 * 18</gadget>
<output>342</output>

<gadget id="calculator">300 + 342</gadget>
<output>642</output>

<result>642</result>