The height of the King's Chamber is quite interesting:

There are 5 courses of 64 digits (with the number 64 perhaps connected to the eye of Horus?)

The floor is 7 digits above the bottom of the lowest course, which means that the intended height was 420 digits minus 7 digits equals 313 digits.

Therefore the height of the King's Chamber equates to 10 royal cubits, plus 1 royal cubit, plus 1 palm, plus 1 digit. This may have appeared to be a fascinating dimension.

The square root of 125 in royal cubits equates to 313 digits, accurate to a very small fraction of a digit.

Petrie interpreted a number of dimensions as the square root of a round number of royal cubits, but for overlooked the vertical height of the Grand Gallery near the north end wall as the square root of 280 royal cubits.

But what proof do we have that the architect used digits?

There are many subtle clues in the design of the Grand Gallery:

The difference between the perpendicular lap height of 43 1/2 digits and the bench height of 28 1/2 digits is 15 digits, and the difference in vertical height is equal to the square root of 280 digits
The perpendicular height of the gallery is 15 royal cubits and the vertical height of the gallery is equal to the square root of 280 royal cubits from the slope of the floor.

Mark