在excel中如果一个单元格中一下任意一个数时用，如何用以下符合表示?

Question

在excel中如果一个单元格中一下任意一个数时用，如何用以下符合表示?
1、2、3、4、5、6、7、8、9、10、11、12

1、2、 9用a或1及其他符合表示
3、4、10用b或2及其他符合表示
5、6、11用c或3及其他符合表示
7、8、12用d或4及其他符合表示

Answer 1

假设数字写在A1单元格,则B1单元格写入公式
=IF(OR(A1="",A1<1,A1>12),"",CHOOSE(A1,"a","a","b","b,"c","c","d","d","a","b","c","d"))
或
=IF(OR(A1={1,2,9}),"a",IF(OR(A1={3,4,10}),"b",IF(OR(A1={5,6,11}),"c",IF(OR(A1={7,8,12}),"d",""))))
再或
=IF(OR(A1="",A1<1,A1>12),"",VLOOKUP(A1,{1,"a";2,"a";3,"b";4,"b";5,"c";6,"c";7,"d";8,"d";9,"a";10,"b";11,"c";12,"d"},2,))

=IF(OR(A1="",A1<1,A1>12),"",LOOKUP(A1,{1,"a";2,"a";3,"b";4,"b";5,"c";6,"c";7,"d";8,"d";9,"a";10,"b";11,"c";12,"d"}))