How to multiply DataTable column with all other column in c#

Question

How to multiply datatable columns with all other columns in  same datable. find the below details for understanding:

 

 

i have the following datatable in C# code behind file:

col4	col3	col2	col1
8	5	1	1
9	2
7	4

 

expecting result:

col4	col3	col2	col1
8	5	1	1
8	2	1	1
8	4	1	1
9	5	1	1
9	2	1	1
9	4	1	1
7	5	1	1
7	2	1	1
7	4	1	1

 

Every column multiply with all other column which is make the unique row. see the above tables