Do the following operations on a number: multiply by 4, add 112, subtract 20, and finally divide by 4 to get 100. So what is this number?
将一个数做如下运算：乘以4，再加上112，减去20，最后除以4，这时得100．那么这个数是多少．
<gadget id="calculator">100 * 4</gadget>
<output>400</output>

<gadget id="calculator">20 - 112</gadget>
<output>-92</output>

<gadget id="calculator">400 + (-92)</gadget>
<output>308</output>

<gadget id="calculator">308 / 4</gadget>
<output>77</output>

<result>77</result>