Last Month End = This Month Beginning

[SofiaD]

Hi Everyone!

Can anyone assist with this?

Looking to find a way to get last month ending numbers per salesperson 

as this month's beginning numbers in Power Query Editor

Jan begining numbers come from a customer list (table 1)

Then monthly we add/lose customers (from an addition table (table 2) and a lost table(table 3))

Ending numbers in Jan become Feb starting numbers

Again add/lose customer (table 2 & 3 again)

Feb ending becomes Mar starting and so on

Ex.

Date	Salesperson	Beg Customer Count	Added Customer	Lost Customers	Ending Customers
1/1/2018	A	5	1	-2	4
1/1/2018	B	6	2	-2	6
1/1/2018	C	4	3	-1	6
2/1/2018	A	4	3	-1	6
2/1/2018	B	6	1	-4	3
2/1/2018	C	6	2	-1	7
3/1/2018	A	6	5	-3	8
3/1/2018	B	3	2	-1	4
3/1/2018	C	7	2	-3	6

Any idea how I can achieve this?

Thanks in advance!!

[v-chuncz-msft · Accepted solution]

@SofiaD,

You may take a look at https://community.powerbi.com/t5/Desktop/M-Function-calculate-running-total/td-p/358212.