Fang Fang poured 640ml of water into 4 small cups and 1 large cup, and they were all filled up. The capacity of the small cup was 1/4 of that of the large cup. What is the capacity of the cup in milliliters?
芳芳把640毫升水倒入4个小杯和1个大杯，正好都倒满，小杯的容量是大杯的(1/4)．则大杯的容量是多少毫升．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 4</gadget>
<output>1</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">640 / 2</gadget>
<output>320</output>

<result>320</result>