Arrange 27 □ in 6 rows, if 5 □ are placed in each row, how many □ are left?
把27个□摆成6排，如果每排要摆5个□，还差多少个□．
<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<gadget id="calculator">30 - 27</gadget>
<output>3</output>

<result>3</result>