title: different result 22/7 on python 2.7.12 and 3.6
body: <p>how to make output <code>22//7</code> on python 2.7 become <code>3.14159</code> ?i try use <code>float(22/7)</code> but it just give me <code>3.0</code>. I try use <code>Decimal</code> but it just give me <code>3</code>, use <code>round(x, 6)</code> only give <code>3.0</code> just like <code>float</code>. </p>