A bottle of shampoo is 1 liter in total, and 280 milliliters have been used. If you need to use 16ml to wash your hair once, how many times can you use this bottle of shampoo?
一瓶洗发水共1升，已经用去了280毫升．如果洗一次头发需要用16毫升，这瓶洗发水还可以用多少次？
<gadget id="calculator">1_000 - 280</gadget>
<output>720</output>

<gadget id="calculator">720 / 16</gadget>
<output>45</output>

<result>45</result>