Editing Napier's bones (section)

== Diagonal modification ==
During the 19th century, Napier's bones were transformed to make them easier to read. The rods were made with an angle of about 65° so that the triangles that had to be added were aligned.  In this case, in each square of the rod the unit is to the right and the ten (or the zero) to the left.

[[Image:Napier Modification.png]]

The rods were made such that the vertical and horizontal lines were more visible than the line where the rods touched, making the two components of each digit of the result easier to read. Thus, in the picture it is immediately clear that:
:{{nowrap|1=987654321 × 5 = 4938271605}}