nCr（二項係数）の面白い解法【今週の数オリ#12】

========== We are currently recruiting participants for our "Complete Answers for Top Universities Math Series," which aims to steadily close the gap between the Blue Chart and entrance exams and solve all problems perfectly using thought processes and first-time approaches! If you're interested, please sign up for our Math LINE account. ↓↓ https://lin.ee/fpWlPtEx (If you've already added us, please block and unblock us.) ========== This week's Math Olympiad is every Tuesday at 6:30 AM! Based on problems from the Math Olympiads in Japan and overseas, let's share our thought processes and ways of thinking that are relevant to university entrance exams. As a rule, be sure to share any insights or discoveries you've learned in the comments! It's a good habit to make. You can immediately use the three key solutions you learned in the explanations of all integer problem patterns.    • 【整数問題】入試頻出解法を”４時間で”全パターン解説   Mod (congruence equation) - All patterns explained    • 【整数問題】mod（合同式）をたった１本で全解説   #ThisWeek'sMathOlympiad #MathOlympiad #PassLab