The capacity of a barrel of milk is 2 liters. Fang Fang drinks 300 ml of milk every day for 6 days, how many ml is left.
一桶牛奶的容量是2升，芳芳每天喝300毫升牛奶，喝了6天，还剩多少毫升．
<gadget id="calculator">2 * 1_000</gadget>
<output>2_000</output>

<gadget id="calculator">300 * 6</gadget>
<output>1_800</output>

<gadget id="calculator">2_000 - 1_800</gadget>
<output>200</output>

<result>200</result>