20190119土 晴れ 11⇔2 西北西2 分数計算テクニック --- LibreOffice数式(Math)のソース： {1} over {2} + {1} over {6} + {1} over {12} + {1} over {20} + {1} over {30} + {1} over {42} + {1} over {56} + {1} over {72} + {1} over {90} = {1} over { 1 …