Help with Column Calculation

[bhorvati]

I need to create a calculated column "Total Units" that totals the unit sales by Order Number without reference to row context.   I need the total as a calculated column since I will create a new dimension based on the size of the total.   Unit Category = if [Total Units] < 100000 then "Small" else "Big"

See example below.  I need a formula so that for each row where it shows order number "1000", that the new Total Units column total is 75,000.

This seems like it should be easy, but I have spent all day trying to figure this out.   Sorry, I'm a newbie. 

[MattAllington · Accepted solution]

=calculate(sum(table[units]),filter(table,table[ordernumber]=earlier(table[ordernumber]))

be sure to write only 1 calculated colum, not 2. Get the one above working first, then modify it to return "big" or "small". This is better than having 2 columns

[bhorvati]

Worked perfect Matt.  Thanks so much.   I had not even heard of the EARLIER function until just now.