How to change cell based on another cell value on Google Sheets

Question

I have a Google sheet got more than 10,000 rows, so I want to change cell value based on another cell, e.g column B has 200 rows out of this 200 rows there are 74 rows have value 910, I want to change column C based on column B so if column B has 910 value change column C value to "Hail" on the same row that has 910 on B column.

Answer 1

paste this into C1 cell:

=ARRAYFORMULA(IF(B1:B=910; "Hail"; ))