In addition to the challenge’s requirements, i added few extras such as a backspace, formatting for thousand’s separator e.g, 1000 is shown as 1,000. And decimal number support. All this took a fair bit of extra work but i am quite happy with the end product. Take a look
BTW: i am going to my first coding meetup in Melbourne (Australia) on Tuesday 21st. Looking forward to meeting some of you there.