The flour extraction rate of a batch of flour processed by a flour mill is 70%. If 210 kilograms of flour are to be processed, how many kilograms of wheat are needed at least?
面粉厂加工一批面粉的出粉率70%，如果要加工出210千克面粉，至少需要小麦多少千克？
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">210 / (7/10)</gadget>
<output>300</output>

<result>300</result>