There is an empty shelf in the warehouse. This shelf has three layers, and each layer can hold 30 parts. If 630 new parts are to be purchased, how many such shelves are more appropriate?
仓库里有一个空货架，这个货架有三层，每层可放30个零件．如果要购进630个新零件，增加几个这样的货架比较合适？
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">630 / 90</gadget>
<output>7</output>

<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<result>6</result>