Sum cells once one has reached a value

[edmdas]

I am trying to sum cells once one has passed a set value (criteria).

I've tried using SUMIF, SUMIFS, COUNTIF, AND formulas in various combinations and searched forums for what appears to be a simple problem, but no joy
I have three cells in columns headed P, M, D (A3,B3,C3). Each can have values from 0 to 17.
I want to add the cells in column P&M (A3, B3) together once the cell in column P is equal to 17, result in the cell D3.

Then when the cells in columns P&M are both equal to 17 (A3, B3) I want to add them to the value in the D column cell (C3).

If this can be combined into one formula that would be fine.

Again, I find the simple calculations harder to formulate than the more complex ones?

Any advice or help appreciated I just know someone has done this before somewhere.

[NBVC]

In D3:

=IF(C3=17,SUM(A3:B3),0)

in E3:

=IF(AND(A3=17,B3=17),D3+17,0)

if you want to combine formulas:

=IF(AND(A3=17,B3=17),IF(C3=17,SUM(A3:B3),0)+17,0)

[edmdas]

Thanks NBVC!

The value in cell D3 varies from 0 to 17 as well so I made a few adjustments which appear to work:

Cell D3 as: =IF(A3=17,SUM(A3:B3),0)

Cell E3 as: =IF(AND(A3=17,B3=17),D3+C3,0)

and the combined formula as: =IF(AND(A3=17,B3=17),SUM(A3:C3),0)

Could you just check my logic here?

Thanks for the pointer, this will be very useful elswhere

[NBVC]

Looks okay to me.

[edmdas]

Thanks! - works great