Group by Sum in Excel

Question

Let's assume that I have the following table in Excel

A     B
Item  quantity_sold
A     3
A     4
A     1
B     5
B     2
D     12
C     3
C     7
C     8

and I need to sum up quantity_sold grouped by Item and print the results on the adjacent column only once per group, similar to the following

A     B                 C   
Item  quantity_sold    SUM_by_item_type
A     3                 8
A     4
A     1
B     5                 7
B     2
D     12                12
C     3                 18
C     7
C     8

Is there any way I can achieve this without using Pivot Tables?

Answer 1

It is very easy and you can do it with a simple formula 

if u select the next column for rearranging the data and type the formula =IF(A2=A1,"",SUMIF(A:A,A2,B:B))

Here A2 is a relative cell you want to sum  based on, A1,A is the column you want to sum based on the B column you want to sum the values