shopping mall sells a preferential shopping card. After buying this card for 200 yuan, you can enjoy a 20% discount in this shopping mall with this card. When shopping for how many yuan, is it cost-effective to buy this kind of shopping card?
某商场出售一种优惠购物卡，花200元买这种卡后，凭此卡可在这家商场享受八折优惠．在购物多少元时，买这种购物卡合算？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">200 / (1/5)</gadget>
<output>1_000</output>

<result>1_000</result>