The box originally contained 6 red balls and 1 white ball. Then put how many white balls with the same weight, size and feel. The probability of touching the white ball from the box is (1/3).
盒子原有6个红球，1个白球．再放入多少个重量、大小和手感都相同的白球．从盒子里摸到白球的可能性是(1/3)．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) * 6</gadget>
<output>2</output>

<gadget id="calculator">(1/3) - 1</gadget>
<output>-2/3 = around -0.666667</output>

<gadget id="calculator">2 + (-2/3)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(4/3) / (2/3)</gadget>
<output>2</output>

<result>2</result>