JSFiddle - React, Tailwind, and code Playground

HTML

<label>Number of Shares:</label><input name="shares" id="shares" type="text" />
<br />
Total Value: &euro; <span id="result"></span>

JavaScript

$(document).ready(function(){
    $('#shares').keyup(function(){
        $('#result').text($('#shares').val() * 1.5);
    });    
});