Stack 7 identical books, the height is 42 mm. If 28 such books are stacked up, how many millimeters will be the height? (answer in a different way)
把7本相同的书摞起来，高42毫米．如果把28本这样的书摞起来，高多少毫米？(用不同的方法解答)
<gadget id="calculator">42 / 7</gadget>
<output>6</output>

<gadget id="calculator">6 * 28</gadget>
<output>168</output>

<result>168</result>