Add Column Cumulative Total in Power Query

[Anonymous]

I have a table containing Month and Value and would like to add one column with cumulative total. 

Below is the example I had:

The logic is:

MONTH 1 = 0

MONTH 2 = Value MONTH 1

MONTH 3 = Value MONTH 1 + Value MONTH 2

MONTH 4 = Value MONTH 1 + Value MONTH 2 + Value MONTH 3

...

MONTH 9 = Value MONTH 1 + Value MONTH 2 + Value MONTH 3 + Value MONTH 4 + Value MONTH 5 + Value MONTH 6 + Value MONTH 7 + Value MONTH 8.

Since I have value until MONTH 8, therefore new row should be added which is MONTH 9 (summation of value MONTH 1 until MONTH 8). 

So far my solution is to add column and use this condition (which I find probably make POWER BI become slower) and I am unable to add one more row which is MONTH 9:

= Table.AddColumn(#"Previous Query", "CUMULATIVE", each if [MONTH] = 1 then 0 else if
[MONTH] = 2 then #"Previous Query"[VALUE]{0} else if
[MONTH] = 3 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1} else if
[MONTH] = 4 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2} else if
[MONTH] = 5 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2}+#"Previous Query"[VALUE]{3} else if
[MONTH] = 6 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2}+#"Previous Query"[VALUE]{3}+#"Previous Query"[VALUE]{4} else if
[MONTH] = 7 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2}+#"Previous Query"[VALUE]{3}+#"Previous Query"[VALUE]{4}+#"Previous Query"[VALUE]{5} else if
[MONTH] = 8 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2}+#"Previous Query"[VALUE]{3}+#"Previous Query"[VALUE]{4}+#"Previous Query"[VALUE]{5}+#"Previous Query"[VALUE]{6} else if
[MONTH] = 9 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2}+#"Previous Query"[VALUE]{3}+#"Previous Query"[VALUE]{4}+#"Previous Query"[VALUE]{5}+#"Previous Query"[VALUE]{6}+#"Previous Query"[VALUE]{7} else if
[MONTH] = 10 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2}+#"Previous Query"[VALUE]{3}+#"Previous Query"[VALUE]{4}+#"Previous Query"[VALUE]{5}+#"Previous Query"[VALUE]{6}+#"Previous Query"[VALUE]{6}+#"Previous Query"[VALUE]{7}+#"Previous Query"[VALUE]{8} else if
[MONTH] = 11 then #"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2}+#"Previous Query"[VALUE]{3}+#"Previous Query"[VALUE]{4}+#"Previous Query"[VALUE]{5}+#"Previous Query"[VALUE]{6}+#"Previous Query"[VALUE]{6}+#"Previous Query"[VALUE]{7}+#"Previous Query"[VALUE]{8}+#"Previous Query"[VALUE]{9} else
#"Previous Query"[VALUE]{0}+#"Previous Query"[VALUE]{1}+#"Previous Query"[VALUE]{2}+#"Previous Query"[VALUE]{3}+#"Previous Query"[VALUE]{4}+#"Previous Query"[VALUE]{5}+#"Previous Query"[VALUE]{6}+#"Previous Query"[VALUE]{7}+#"Previous Query"[VALUE]{8}+#"Previous Query"[VALUE]{9}+#"Previous Query"[VALUE]{9})

I would appreciate if someone can provide me much more simpler calculation

[Anonymous]

Hi  @Anonymous ,

Please use the following M to add a custom column:

=List.Sum(List.FirstN(#"Changed Type"[VALUE],[MONTH]-1))

Best Regards,
Eyelyn Qin
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[HotChilli · Accepted solution]

I'm posting some code for the cumulative column here:

Table.AddColumn(#"Previous Query", "Custom", each List.Sum(List.Range(#"Previous Query"[VALUE], 0, [MONTH]-1)))

May I request that you post data (not a picture) next time, for quicker answers?

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If you want to add a row, you can create a one row table and append it (before adding the custom column above).  I haven't tried it but it should work