Numbers 
Merge and unmerge cells
Merging table cells combines adjacent cells into a single cell. You can unmerge cells as well, and all the data is retained in the new top-left cell.
You can only unmerge cells that were previously merged; you can’t split a cell.
Note: You can’t use forms for tables with merged cells. Forms in a Numbers for iOS spreadsheet are hidden when you open the spreadsheet in Numbers for Mac. In Numbers for Mac, merging cells in a table linked to a form may clear the form.
Merge and unmerge cells
Do one of the following:
-
Merge cells: Select two or more cells, then choose Table > Merge Cells (from the Table menu at the top of your computer screen).
These are the results of merging cells:
If only one of the cells contains content prior to merging, the merged cell retains the content and formatting of that cell.
If multiple cells contain content before merging, all the content is retained, but cells with a specific data format, such as numbers, currency, or dates are converted to text.
If a fill color is applied to the top-left cell, the merged cell takes on the fill color.
-
Unmerge cells: Select the cell, then choose Table > Unmerge Cells (from the Table menu at the top of your computer screen).
All of the content from the previously merged cell appears in the first unmerged cell.
You can’t merge cells from different areas in the table—for example, a body cell and a header row cell.
Tip: Merged cells are treated specially in formulas:
To refer to the cell directly in a formula, use the address of the merged cell’s top-left corner.
You can’t include only part of a merged cell in a cell range that’s used in a formula.
If you refer to a cell in a formula, then merge the cell with cells that are outside the formula’s intended range, the formula may result in an error.