Numbers is built differently from the ground up, so there's no cell merging. Instead of having one giant field of cells per tab, each tab is a blank page into which you drag/drop tables of cells, each of which has their own headers and formatting.
I don't know how well it works on iPhone. The iPad version rules.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -