Require formula for lot wise sum.

[nitishshr]

I require specific formula for lot wise sum of ID .
The ID will re-occur but the re-occurred ID should be separately addition-ed.
The ID will be nearly in 2000 number.
# Do not sum all the similar Structure ID
#Do not change the Structure ID

Structure ID	Weight	SUM
A	1
A	1	3
B	2
B	3	5
G	3
G	4	7
A	5
A	6	11
B	7
B	6	13
R	4
R	3	7
G	2	2

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[Special-K99]

How do you get 3 in the second row of SUM ? I make 1+1 equal to 2

 

[Special-K99]

in C2
=IF(A2=A3,"",SUM(B$1:B2)-SUM(D$1:D1))
and copy down

 

[nitishshr]

Thank you Special-K99.

 

[nitishshr]

I was unable to edit . after posting it.

>>(2)

Thank you once again.