JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="Qty" value="3" />
<span id="pricetag">40.00</span>

JavaScript

var qty = $('#Qty').val(); 
var price = '\u00A3' + parseInt($('#pricetag').text().replace(/^\D/, ''), 10) * qty;
alert(price);