Add 24 to 12 (the first operation), then subtract 20 (the second operation), add 24 (the third operation), and then subtract 20 (the fourth operation)... follow this rule , at least how many calculations can be done to get 2012.
将12加上24(第1次运算)，再减去20(第2次运算)，再加上24(第3次运算)，再减去20(第4次运算)…按此规律运算下去，最少经过多少次计算，能得到2012．
<gadget id="calculator">2_012 - 12</gadget>
<output>2_000</output>

<gadget id="calculator">2_000 - 24</gadget>
<output>1_976</output>

<gadget id="calculator">1_976 / 4</gadget>
<output>494</output>

<gadget id="calculator">494 * 2</gadget>
<output>988</output>

<gadget id="calculator">988 + 1</gadget>
<output>989</output>

<result>989</result>