JSFiddle - React, Tailwind, and code Playground
HTML
<input type='val_a' id='a'>
/<input type='val_b' id='b'>
<button id='startbtn'>Start</button>
JavaScript
function division() {
a = document.getElementById('val_a').value()
b = document.getElementById('val_b').value()
c = a%b
alert(a)
alert(b)
alert(c)
}
document.getElementById("startbtn").onclick = division;