measure vs column

This is expected, there is nothing to aggregate when you are at the lowest granularity (or say row-level )

hence, sheet(price)=sum(sheet(price))   -----

As mentioned by @bcharger 1000 is nothing but (10+20+30+40) * (1+2+3+4)=100*10=1000 because the measure will aggregate since it has got a chance to summarise for the 4 rows while for row-level it will sum up the values you see at the rows

See it this way, 

----EXPLANATION OF THE DIFF IN THE TOTAL PART -------

TOTAL (SUM(PRICE) * SUM(QUANTITY))  ------ 

>>> SUM(PRICE)Let me first aggregate for the 4 rows 

>>>SUM(QUANTITY)  Let me first aggregate for the 4 rows

>>> Now do the multiplication 

>>> Now TOTAL of the same

While in the former case

its PRICE * QUANTITY (No Sum) hence you get the individual rows multiplication

At the end you do the TOTAL

That set

Regards,

Ritesh

Regards,

Ritesh