Teacher Zhang wants to buy a down jacket of a certain brand. The price is 850 yuan. The slogan of the shopping mall is: 20% off all products in this shopping mall. How much does Mr. Zhang actually pay for this down jacket?
张老师要买一件某品牌的羽绒服，标价是850元，商场广告语是：本商场所有商品一律八折，张老师买一件这款羽绒服实际要花多少钱？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">850 * (4/5)</gadget>
<output>680</output>

<result>680</result>