Multiple of 3 but 1 line shifted. Here is an example:

`old part number1084 2000 new part number old part number1084`

old part number1085 2001 new part number old part number1085

old part number1086 2002 new part number 2003 new part number

old part number1087 2003 new part number old part number1087

old part number1088 2004 new part number old part number1088

old part number1089 2005 new part number 2006 new part number

old part number1090 2006 new part number old part number1090

old part number1091 2007 new part number old part number1091

old part number1092 2008 new part number 2009 new part number

old part number1093 2009 new part number old part number1093

old part number1094 2010 new part number old part number1094

To produce the 3^{rd} column, write the following formula in the first cell of the 3^{rd} column:

`=IF(MOD(ROW(),3)=0,B2,A1)`

press enter, then double click on the lower right corner of the cell to autocomplete the formula to the next cells of the same column, or alternatively drag the formula down manually. Just an example, the formula can be written in many ways, adjust it to your needs. row() returns the row number of a cell, and mod(a, b) is the modulo function, it returns the remainder of a divided by b. My list separator is comma ',', if yours is something else, e.g. the semicolon character ';' , then in the above formula replace all comma characters with a semicolon character.

If the results must be back in the column A, either make a new copy, or copy the result from the 3rd column and paste it "As Values" over the first column, your choice.