How to total a column on a spreadsheet

add a header or footer row to the table:

This table already has a header row... so let's say we want a sum of column "B" (the one labeled "y")

Add a footer by selecting any cell in the table (to activate the table):

then open the "Table Formatter"

Now change the number of footer rows to "1":

Now select the cell in column B of the footer row (B26 in this example) and type the formula:

=SUM(B)

this formula means to add up the numeric values in every cell in column excluding header and footers)