? = 3.1415926535...
3.1415926535 -> 3.1415926530
3.1415926530 -> 3.1415926500
3.1415926500 -> 3.1415926600
3.1415926600 -> 3.1415926700
3.1415926700 -> 3.1415926800
3.1415926800 -> 3.1415926900
3.1415926900 -> 3.1415927000
3.1415927000 -> 3.1415928000
3.1415928000 -> 3.1415929000
3.1415929000 -> 3.1415930000
3.1415930000 -> 3.1415900000
3.1415900000 -> 3.1416000000
3.1416000000 -> 3.1417000000
3.1417000000 -> 3.1418000000
3.1418000000 -> 3.1419000000
3.1419000000 -> 3.1420000000
3.1420000000 -> 3.1400000000
3.1400000000 -> 3.1000000000
3.1000000000 -> 3.0000000000
3.0000000000 = 3
? = 3