What is the probability that two 1-dollar coins are tossed in the air at the same time, and the two coins land one head and the other tails
向空中同时抛两枚1元硬币，落下后两枚硬币一正一反的可能性是多少
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * (1/2)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>