JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="number" class="num" maxlength="2"/>

JavaScript

$(".num").on('keypress', function(e){
    if (e.keyCode == 50) {
        var input = $(e.target);
        input.val(input.val() + '2/');
        input.focus();
        e.target.setSelectionRange(0,0);
    }
});