Calculator App - Trigger click event for a span tag. Need Help

Hi Everyone,

I need help triggering the on click event on a span tag. After researching a bit on stack overflow, I found out that I am supposed to use the (document).on("click","id","function(){});** and not **( “#target” ).click(function() {}.
But I am still not able to traverse through the span tag which has id=“7”. The idea is to display the number 7 when clicked on span tag 7. Can anybody help me achieve this?

Thank you!

Thank you rmdawswon71! Adding JQuery library did the trick. Sometimes, we tend to overlook the important little things. It is working perfectly now.