1.You can directly copy from this ipynb file and paste in google collab or jupyter notebook or any other similar thing.
2.To evaluate any single operation expression just draw that in paint and upload it on google drive or just simply save it and paste its address in 10th cell in the 1st line in cv2.imread('path') and simply run.
NOTE:- you can even scan the image and do the same thing but its recommended to draw in paint and do because due to bad picture quality the classifier may not identify the numbers or symbols correctly.