Spreadsheet: Sum of dynamic number of rows - google-sheets

Question

I have a table in my Google Spreadsheet that looks like this :
Row
(A) Some day
(B) Some data
1
day 1
5
2
day 2
10
3
total
4
day 1
8
5
day 2
7
6
day 3
9
7
total
Where I can have multiple "day rows", but I don't know how many. It can be only 1 like it can be 20 "day rows". And I want the "total row" to automatically do a SUM of the "day rows" above.
Result expected :
Row
(A) Some day
(B) Some data
1
day 1
5
2
day 2
10
3
total
15
4
day 1
8
5
day 2
7
6
day 3
9
7
total
24
Where B3 is equal to SUM(B1:B2) and B7 is equal to SUM(B4:B6)
I am trying to do that without the App Script, just using Spreadsheet native functions.
I think I should be using the SUM function or the Query function, but I don't know how to dynamically get the right range. Do you have any idea how to do that ?
Thank you

Answer 1

In your example, column B would be a mixture of constants and formulas. That would require a script to deposit the formulas. However with an extra column, you can avoid scripts. In C2 enter:
=if(A2<>"Total","",sum($B$1:$B1)-sum($C$1:C1))
and copy downwards:
Basically we add column B and subtract any previous Totals in column C.

Answer 2

Another approach is to place the following single array formula in C1:
=ArrayFormula(IF(A:A="",, SUMIF(IF(ROW(A:A),ROW(A:A)), "<="&ROW(A:A),B:B) - SUMIF(IF(ROW(A:A), ROW(A:A)),"<="& VLOOKUP(ROW(A:A)-1, FILTER(ROW(A:A), A:A="total"), 1, TRUE), B:B)))
If you only want to see the values for the "total" rows, change the opening
IF(A:A=""
to
IF(A:A<>"total"
The short version of how it works is that a sum is made of all values up to the current row in B:B, and from that is subtracted any values up to the last listing of the word "total" in A:A.

Answer 3

paste in each cell in B column where A column = total
=INDEX(SUM(IFERROR(1*INDIRECT(ADDRESS(MATCH(INDEX(
COUNTIFS({"total";A:A}, {"total";A:A}, {"total";A:A}, "=total",
{ROW(A:A);ROW()}, "<="&{ROW(A:A);ROW()})-1, ROW()+1, 1),
COUNTIFS({"total";A:A}, {"total";A:A}, {"total";A:A}, "=total",
{ROW(A:A);ROW()}, "<="&{ROW(A:A);ROW()}), 0), 2)&":"&
ADDRESS(ROW()-1, 2)), 0)))