【循环】近似计算（approximation）

<p> <!--[if gte mso 9]>Normal07.8 磅02falsefalsefalseMicrosoftInternetExplorer4<![endif]--><span style="font-size:medium;"><span style="font-family:Times New Roman;">&nbsp;&nbsp;&nbsp;&nbsp;计算<span>π</span><span>/4 = 1 - 1/3 + 1/5 - 1/7 +</span>……，直到最后一项小于<span>10</span>^{<span>-6</span>}<!--[if gte mso 9]><![endif]--><!--[if gte mso 10]> <![endif]-->。</span></span> </p> <!--[if gte mso 9]>Normal07.8 磅02falsefalsefalseMicrosoftInternetExplorer4<![endif]-->

<p> <span style="font-size:medium;">&nbsp;&nbsp;&nbsp;&nbsp;无输入。</span> </p>

<p> <span style="font-size:medium;"><span style="font-size:medium;"><span style="font-family:Times New Roman;"><span>&nbsp;&nbsp;&nbsp;&nbsp;π</span><span>的值，</span></span></span>结果精确到小数点六位。</span> </p>