Rangeの範囲 p (1..10).to_a p (1...10).to_a [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] [1, 2, 3, 4, 5, 6, 7, 8, 9] 多重代入とflatten 複数の引数でも、配列でも、どっちでも引数にとれて便利 def f(*params) params.flatten.reduce { |sum, v| sum + v } end p f…