JSFiddle - React, Tailwind, and code Playground

HTML

<input type="number" id="num" name="num"/>
<input type="button" id="btn" value="Изчисли"/>
<div id="result"></div>

JavaScript

$(document).ready(function(){
    var exchangeRate = 0.4323;
    $('#btn').click(function(){
        var num = $('#num').val();
        var result;
        if(exchangeRate > 0){
            result = num / exchangeRate;
        }
        else
        {
            result = "Devision by zero!";
        }
        $('#result').html(result);
    });
});