Hello all Heeeellllpppp!
Cannot get my head around this and now I'm just getting frustrated.
Hope this is correct bit of the forum!

I have a spreadsheet that calculates the index moment of a bar. Along the tube there are fluid containers which drain in a specific order.
I need excel to calculate the remaining fluid in the containers once a certain amount has been removed so I can then calculate the moment before and after.
Its the subtraction bit I cannot get my head around.

example

container 1 starts with 500
container 2 starts with 0
container 3 starts with 8000
container 4 starts with 1000

If i drain 5500 I am left with

container 1 0
container 2 0
container 3 3000
container 4 1000

How can i set it up so that excel does not return native numbers and uses the remainder from calculation 1 to start calculation 2

The answer is most likely straight forward I just cannot see it!!
cheers
Nobby