If a coin is tossed 3 times in a row, what is the probability that at least one of them will come up tails?
一枚硬币连续抛掷3次，至少有一次反面向上的概率是多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * (1/2) * (1/2)</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 - (1/8)</gadget>
<output>7/8 = around 0.875</output>

<result>7/8 = around 0.875</result>