The teacher of the school's letter school department wants to buy 110 pairs of slippers. I saw the same slippers in three stores with different prices and different conditions and discounts: Hualian store 9 yuan per pair, buy 10 get 1 free; star mall 10 yuan per pair, 15% discount; Supermarket, 11 yuan per pair, 25% discount, ask this teacher which store is the cheapest to buy? Why? How much do you need in total?
学校信校部老师要买110双拖鞋，看了三家商店同样的拖鞋价格不同条件优惠也不同：华联商店每双9元，买10送1；星星商场每双10元，八五折优惠；友谊超市，每双11元，优惠25%，问这位老师到哪家商店买最省钱？为什么？一共需多少钱？
<gadget id="calculator">100 * 9</gadget>
<output>900</output>

<result>900</result>