JSFiddle - React, Tailwind, and code Playground
by baacke
HTML
<div id="time"></div>
JavaScript
var secondsInMinute = 60,
testTime = 55,
questions = 40,
secondsPerQuestion = (testTime / questions) * secondsInMinute,
timeLeft = testTime * secondsInMinute;
setInterval(function(){
document.getElementById('time').innerHTML = timeLeft;
timeLeft--;
}, 1000);