(1-(1/(2**2)))*(1-(1/(3**2)))*(1-(1/(4**2)))*…(1-( 1/(15**2))) = how much.
(1-(1/(2**2)))*(1-(1/(3**2)))*(1-(1/(4**2)))*…(1-(1/(15**2)))=多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">16 / 15</gadget>
<output>16/15 = around 1.066667</output>

<gadget id="calculator">(1/2) * (16/15)</gadget>
<output>8/15 = around 0.533333</output>

<result>8/15 = around 0.533333</result>