The cell number is converted to the corresponding letters, "1", "A";" 2 ", "B";" 3 ", "C";" 4 ", "D";" 5, "" E";" 6 ", "F";" 7 ", "G";" 8 ", "H";" 9 "and" I ";" 0 ", "Z", such as 1368 into ACFH, 2600 need to BFZZ