how can I have a running total for a column of numbers

I have two columns of numbers for a budget. B1 through B19 are the data I want B20 to show the total

Hello,

Your question is conflicting. Main question says running total and detail says total. Also detail says two columns but you specify only column B.

If you simply want a total of B1 through B19 see
https://help.libreoffice.org/6.3/en-US/text/scalc/01/04060106.html?DbPAR=CALC#bm_id3163596

OK, I"ve attached a file. but basically:
Col C holds the running total

the 2nd cell (c2)holds the sum of cells 1 and 2 (b1+b2)
the 3rd cell hold C2 plus B3 (c2+b3)
4th cell same (c3+b4)
and so on.

After you set up the first 2 cells, you can copy the formula from the 3rd cell down to the rest.
running-total.ods