After adding a pair of brackets to the formula "7*9+12/3-2", what is the maximum value of the formula?
给算式"7*9+12/3-2"加一对括号后，算式的最大值是多少．
<gadget id="calculator">9 + 12</gadget>
<output>21</output>

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">21 / 1</gadget>
<output>21</output>

<gadget id="calculator">7 * 21</gadget>
<output>147</output>

<result>147</result>