Xiao Ming’s piggy bank has 100 dime coins stored in it. He takes out some of the coins from the tank every day to buy breakfast, takes out (1/10) on the first day, and takes out (1/9) and (1/10) of the existing coins every day thereafter. 8), (1/7)..., how many coins are left after 9 days.
小明的储蓄罐内存1角硬币100个，他每天上学从罐内取出一部分买早点，第一天取出(1/10)，以后每天都取出当中现有硬币的(1/9)、(1/8)、(1/7)…，9天后剩下多少个硬币．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">20 * (1/2)</gadget>
<output>10</output>

<result>10</result>