Is there a formula to display the last number in a column.

I have data rows 1-31 in 12 different columns. I want a to be able to pick
up a the last number entered in each of the columns. So for instance and
have data in rows 1-23 in column A, the data in rows 1-31 ni col B. Is
there a formula to put in row 45 that will pick up the last # entered in a
column.

Thanks for the help.