JSFiddle - React, Tailwind, and code Playground

HTML

<tr>
<td class="tdLable">value1</td>
<td class="tdchoose">

<select id="s1" name="s1" onchange="calculate()" >
<option value="0" >Please select</option>
<option value="10287">• neki tekst1</option>
<option value="9587">• neki tekst2</option>
</select> 
 
</td> 
</tr>
<br>
<tr>
<td class="tdLable">value2</td>
<td class="tdchoose"> 

<select id="s2" name="s2" onchange="calculate()" >
<option value="0" Selected>Please select</option>
<option value="6955">neki tekst3 </option>
<option value="6930">neki tekst4</option>
</select>

</td>
</tr>
<p id="result"></p>

CSS

#result{
    margin: -4% 0% 0% 35%;
}

JavaScript

function calculate()
{
	var s1 = document.getElementById("s1").value;
	var s2 = document.getElementById("s2").value;
	
	if(s1 != "0" && s2 != "0")
	{
		document.getElementById("result").innerHTML = "Result is: " + s1*s2;
	}
	else
	{
		document.getElementById("result").innerHTML = "";
	}
}