When copying/pasting cells from Numbers v6.2.1 into an existing table in Pages v8.2.1, the trick is to click once to select the target cell in the Pages table — not enough to show a blinking insertion point within the cell, but a selection border around the cell.
The following is a copy and direct paste from Numbers v6.2.1 selection into cell A1 of Pages v8.2.1 Table 1. The formula in the yellow cells pasted intact.


And the formula that pasted into cell F2 of the Pages table:

The table support in Pages v8.2.1 is a subset of that in Numbers, and some cell data format omissions in Pages remind you of it.