Below is a possible solution to the challenge Challenge 37 – Find nth Alphabet from the Bottom.
Put following formula as Array formula in E1
=IF(SUM(–(ABS(77.5-IFERROR(CODE(UPPER(A1:A100)),0))<13))>=C1,
INDEX(A1:A100,LARGE((ABS(77.5-IFERROR(CODE(UPPER(A1:A100)),0))<13)
*ROW(A1:A100),C1)),"")
Note – Array Formula is not entered by pressing ENTER after entering your formula but by pressing CTRL+SHIFT+ENTER. If you are copying and pasting this formula, take F2 after pasting and CTRL+SHIFT+ENTER. This will put { } brackets around the formula which you can see in Formula Bar. If you edit again, you will have to do CTRL+SHIFT+ENTER again. Don't put { } manually.
The workbook containing the solution can be downloaded from Solution – Challenge 37 – nth Alphabet from the Bottom.