The Paradox of 1 – 1 + 1 – 1 + 1 – 1 + …

" Here’s a math problem that everybody can solve: What is 1 − 1? 0. So far so good. If we then add a 1, the sum grows, but if we subtract yet another 1, we’re back at 0. Let’s say, we keep doing this forever:

1 – 1 + 1 – 1 + 1 – 1 + ... "

https://www.scientificamerican.com/article/1-the-paradox-of-1-1-1-1-1-1/