Here are a few.
1. Enter 1 in A1. Right-click and drag down 12 rows. Release button and
"Fill Series"
2. Enter 1 in A1, 2 in A2. Select both and left-click drag down 12 rows.
3. Select A1:A12. In A1 type 1 then Edit>Fill>Series>Linear. Enter a Step
Value if you wish.
4. For a unique fill series........Tools>Options>Custom Lists>New. Type your
items in comma-delimited. Enter the first in A1 then left-click drag down.
Gord Dibben Excel MVP