crow is thirsty. It finds a bottle. The water in the bottle is 6cm high. The crow can’t drink the water. After it puts a few stones into the bottle, the water rises by 1/2, but it still can’t drink. When it reaches the water, it puts a few more stones. This time the height of the water rises is (2/3) of the height of the first water rise. At this time, the crow happily drinks the water. You know that when the crow drinks the water, , How many centimeters has the height of the water risen from the original?
一只乌鸦口渴了，它发现一个瓶子，瓶子里水高6cm，乌鸦喝不到水，它向瓶子里放了几块石子后，水升高了原来的(1/2)，还是喝不到水，它又放了几块石子，这次水升高的高度是第一次水升高的高度的(2/3)，这时乌鸦高兴地喝到了水，你知道乌鸦喝到水时，水的高度比原来升高了多少厘米吗？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

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

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<result>5</result>