The LASTINDEXOF function returns the index of the last occurrence of one text string within another text string.
=LASTINDEXOF("This is great.", "is")
would return 5. "is" can be found at both index 2 and 5, bit 5 is later in the string so 5 is returned.
- within_text - Required. The text containing the text you want to find.
- find_text - Required. The text you want to find.