Matching Row# to Cells with multiple Data

[rusty_J]

I am building an index function with some success, but I need to find a way to use the MATCH formula (or something similar) to give a row#, however some cells contain multiple values.

(Our purchase orders are 7 digits long.)
So, for example

Purchase Order Column
1: 1521234
2: 1731248
3: 1951254
1551266
4: 1256478

Say I need it to find 1551266, how can I get it to return "3" to indicate which row it is in?

Let me know if any further explanation is needed. Thanks!