There is a website where you can prove these things one by one, they made a little game out of it, using the leanprover software. I highly recommend it! https:

There is a website where you can prove these things one by one, they made a little game out of it, using the leanprover software. I highly recommend it! https://www.ma.imperial.ac.uk/~buzzard/xena/natural_number_game/ https://www.ma.imperial.ac.uk/~buzzard/xena/natural_number_g...