Thanks for the info to all of you.

I selected column (C) which was my Length column, went to Data / Validation / and entered the formula from one of the websites you provided: =COUNTIF($C$1:$C$50,C1)=1

I got it to work for that one column but there is one more constraint that I'm dealing with for column (G) also.

Below, you can see the chart I'm using. I need to know when I have a duplicate (Length+Remarks).
For example: I have a part that is 1'-11 3/4" with a 22'-3" RAD, and I want to be warned if I accidentally enter another part 1'-11 3/4" with a 22'-3" RAD.

Thanks.
Andy


MK/SHT REQ'D LENGTH SECTION C.F. C.F. EXT. REMARKS
41 / 4.0 1 1'-11 3/4" 3/2.0 0.26 0.26 22'-3" RAD
42 / 4.0 28 1'-11 9/16" 3/2.0 0.26 7.15 22'-3" RAD
43 / 4.0 1 2'-1 1/16" 3/2.0 0.27 0.27 22'-3" RAD
44 / 4.0 2 1'-10 9/16" 3/2.0 0.24 0.49 7'-9" RAD
45 / 4.0 11 1'-10 3/8" 3/2.0 0.24 2.67 7'-9" RAD
46 / 4.0 2 1'-9 7/8" 3/2.0 0.24 0.47 8'-1" RAD
47 / 4.0 5 1'-9 11/16" 3/2.0 0.23 1.17 8'-1" RAD
48 / 4.0 2 1'-10 1/8" 3/2.0 0.24 0.48 7'-0" RAD
49 / 4.0 4 1'-9 15/16" 3/2.0 0.24 0.95 7'-0" RAD
50 / 4.0 2 1'-10 13/16" 3/2.0 0.25 0.49 6'-0" RAD
51 / 4.0 3 1'-10 5/8" 3/2.0 0.25 0.74 6'-0" RAD

52 / 4.1 1 1'-11 5/8" 3/2.0 0.55 0.55 22'-3" RAD
53 / 4.1 28 1'-11 7/16" 3/2.0 0.55 15.31 22'-3" RAD
54 / 4.1 1 2'-1 1/16" 3/2.0 0.58 0.58 22'-3" RAD
55 / 4.1 2 1'-10 5/16" 3/2.0 0.52 1.04 7'-9" RAD
56 / 4.1 11 1'-10 1/8" 3/2.0 0.52 5.68 7'-9" RAD
57 / 4.1 2 1'-9 9/16" 3/2.0 0.50 1.01 8'-1" RAD
58 / 4.1 5 1'-9 3/8" 3/2.0 0.50 2.49 8'-1" RAD
59 / 4.1 2 1'-9 13/16" 3/2.0 0.51 1.02 7'-0" RAD
60 / 4.1 4 1'-9 5/8" 3/2.0 0.50 2.02 7'-0" RAD
61 / 4.1 2 1'-10 7/16" 3/2.0 0.52 1.05 6'-0" RAD
62 / 4.1 3 1'-10 1/4" 3/2.0 0.52 1.56 6'-0" RAD