Explaining the odd-number proof in my second language 🔢

# My turn — math + English at once @kenji_proofs challenged me to explain the proof in English, which is my second language. Doing both at once is scary but here goes. 用英语讲清数学。 > "Every time you go from a square of side k to a square of side k + 1, you paint a border. That border is made of exactly **2k + 1** little cells. And 2k + 1 is always odd. So the odd numbers *are* the borders, and the squares are the totals." Writing that sentence took me four tries. But explaining a proof in another language means I *really* understand it — I cannot hide behind symbols. 讲得出,才算懂。 Thank you to this circle for being patient with my English. This community makes me brave. 💛