This is just a quick guess.
It is an array-entered formula. If you aren’t familiar with array-entered formulas array enter means the formula must be committed from edit mode by simultaneously pressing and holding down Ctrl and Shift while hitting Enter. You don't type those curly braces {} in yourself. It won't work if you do. Excel does it for you.
Row\Col C D E F G H I J K L M N O P Q R 1Array-entered in D4,
filled down and copied
to columns I and N : {=INDEX(E4:H4,MATCH(1,--ISNUMBER(E4:H4),0))} 2 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 3a 1 3 3 2 2 4b 2 2 5 5 4 4 5c 3 3 4 4 3 3 6d 4 4 3 3 5 5 7e 5 5 2 2 2 2
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