Why Does 1+1 Equal 2

https://youtube.com/watch?v=S5zyv2yfGn0&si=aiWZhrhae8kommP9

A university mathematics department I used to attend appeared on a certain YouTube program. Hearing the familiar school bell and seeing the classroom again after so long made me feel a bit nostalgic.

One of the intriguing questions shown even in the thumbnail was, “Why is 1+1 equal to 2?” Since it’s been years since I distanced myself from mathematics, I too felt quite lost and curious about it.

The professor’s answer to this was, “Depending on the definition, it could be 0, it could be 1, or it could be 2.” Hearing that brought back a lot of old memories.

If you think of 1+1 as adding one more to one, then of course it’s 2.

If you think of 1 as a 180-degree rotation, then rotating 180 degrees and then another 180 degrees brings you back to where you started. It’s the same as doing nothing at all. Seen this way, 1+1=0.

It all depends on how you define what 1 is, what addition is, and what the equals sign is.

Since I feel like I’ll forget this again in a few years, I’m jotting it down briefly on my Naver blog as well.