PHP combine multiple drop down value in if condtion

I am getting stuck with a problem for three weeks. The problem is that, I have 3 drop down boxes like Select 1 Select 2 and Select 3. All the three boxes having 5 options each having value 0,1,2,3,4.

<select name="select1">
<option>0</option>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
</select>

<select name="select2">
<option>0</option>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
</select>

<select name="select3">
<option>0</option>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
</select>

I would like to do some action based on the value of drop down being selected. I know that, in this way there will be 5*5*5 combination needed which is not a handy process. Is there any easy method to do action based on the option selected on these three drop down boxes.