The doctor prescribed a bottle of medicine for grandpa, and the label on the bottle said "0.2mg (mg) * 252 tablets". The prescription written by the doctor said: "Three times a day, 0.6mg each time, 7 days is a course of treatment." How many courses of treatment can the grandfather take for the medicine prescribed by the doctor?
医生给爷爷开了一瓶药，药瓶标签上写着"0.2mg(毫克)*252片"．医生开的处方上写着："每天3次，每次0.6mg，7天为一个疗程．"医生给爷爷开的药可供爷爷服几个疗程？
<gadget id="calculator">0.6 / 0.2</gadget>
<output>3</output>

<gadget id="calculator">3 * 3 * 7</gadget>
<output>63</output>

<gadget id="calculator">252 / 63</gadget>
<output>4</output>

<result>4</result>