例: 2.317=2.3171717… =2.3+17+1717 +… 103105107 1147 1 495 100 ++4++5 9 π=3 10100100010000100000 例: 3 5 7 3 3 0 2.317 2.3171717 17 17 17 2.3 10 10 10 17 1 17 1 1147 2.3 2.3 . 10 100 10 495 1 1 100 1 4 1 5 9 3 10 100 1000 10000 100000 n n