Just out of interest:
SUM() will ignore text, as you found out, but some other functions in Excel do an implicit conversion
Enter ="1" in A1 and
="2" in A2
Make sure you enter the = sign and the quotes.
This puts 1 and 2 as text in the two cells.
In another cell enter =SUM(A1:A2)
The result is 0
but enter =A1+A2
and the result is 3