The main unit of measurement in ancient Egypt was the royal cubit. This was roughly the length of a man's forearm (elbow to fingertip) and measured 52.4cm. The exact length of a cubit changed during Egyptian history, however. The hieroglyph showing the forearm was used to mean a cubit: .

The cubit was divided into thumb widths. Four thumb widths made a palm, and there were seven palms in a cubit - thus 28 thumb widths.

The ruler below is a copy of one found in the tomb of Maya, a chief of the treasury. Along the bottom we see numbers - various ways of dividing the cubit up.

Along the top, however, are the names of gods - each thumb unit was governed by its own god. From the right it begins with Ra. The fifth god is Osiris, followed by Isis. Number 13 is Thoth.