Hi cc,
When you copy a cell, you copy the formula in the cell, the last result of its calculation, and any formatting that has been applied to the cell.
When you simply Paste, Numbers pastes everything that was copied. The formulas immediately try to create a new result, but they are looking for cells with the same location relative to their new location as the previous cells were relative to their prior location, and in this case, at least one of those relative locations is to a column that does not exist in the table they're currently in. Hence the invalid reference error.
You can't change what gets copied (except in the case of pressing option-command-C to copy only the format applied to a cell), but you can control what gets pasted. To paste just the results of the most recent calculation, go Edit > Paste Formula Results.
BTW: You want to sort these values, so you would not want to "copy them as just text." When numbers are copied (and pasted) as Text, they no longer sort like numbers. They are text, and are sorted as text. As Text, these numbers are correctly sorted in ascending order: 0, 1, 10, 100, 11, 19, 190, 199, 2, 3, 33, 4…
"In this example, H2 was the absolute operator for column H, and P1 was the operator for column P."
Actually, the value in H2 was the "fixed number" in your initial description of the formula used in column H. The 'absolute (reference) operator' is the $ symbol, which kept the formula referencing cell H2 as it was filled down the column.
"What I'd like to do is to take all the numbers in column H and all the numbers in column P, copy them into a new column, with one on top of the other, no spaces in between, and then sort them."
Not a problem.
Select the numbers you want to copy from column H, Copy.
Click on the first non-header cell in the single column* you want them in. Go Edit > Pasrte formula results.
Select the numbers you want to copy from column P. Copy.
Click once on the first empty cell in the single column you want the in. Go Edit > Paste formula results.
Repeat for any other columns of numbers you want to add to the single column.
With one or more cells in the single column selected, click on the triangle in the column's reference tab, and choose Sort Descending.
Done.
*Numbers does not sort single columns within a larger table. The 'single column' should be in its own one column table if you do not wish to change the order of other columns in the same table.
Regrds,
Barry