Yucai Primary School decided to buy a water cup for each of the 360 students, and the price of the water cup was 5 yuan. This kind of water cup is sold at a 10% discount in hundreds of supermarkets. Buy 8 and get one free at Dehui Supermarket. Please figure out which one to buy to save money? How much money do you save?
育才小学决定给360名学生每人买一只水杯，水杯标价5元．这种水杯在百家超市打九折出售，在德惠超市买8只送一只．请你算一算到哪家买省钱？省多少钱？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">5 * (9/10) * 360</gadget>
<output>1_620</output>

<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<gadget id="calculator">360 / 9</gadget>
<output>40</output>

<gadget id="calculator">360 - 40</gadget>
<output>320</output>

<gadget id="calculator">320 * 5</gadget>
<output>1_600</output>

<gadget id="calculator">1_620 - 1_600</gadget>
<output>20</output>

<result>20</result>