The sixth grade office bought a pack of white paper and planned to use 20 sheets per day for 28 days. Due to paying attention to saving paper, only 16 sheets are actually used per day. How many days are actually used more than planned?
六年级办公室买进一包白纸，计划每天用20张，可以用28天．由于注意了节约用纸，实际每天只用了16张，实际比计划多用多少天？
<gadget id="calculator">28 / 16</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">20 * (7/4)</gadget>
<output>35</output>

<gadget id="calculator">35 - 28</gadget>
<output>7</output>

<result>7</result>