Now we look at the numbers on Napier’s bone numbered 6 and the lefthand
column of the ruler. We need to read them remembering that
numbers in the same diagonal strip should be added together. In our
case, we obtain: 61, 124, 189, 256, 325, ... Here too we stop before we
go over the number in the grid. In our case we stop at 256, because the
next number, 325, is larger than the 304 in the grid. We write 256
below 304. 256 comes from the fourth row, so we write 4 to the left of
the number outside the grid. It is the second digit of the answer. The
middle column of the ruler, where on row 4 we find the number 8, tells
us now to take Napier’s bone numbered 8 and to place it to the left of the ruler, moving the bone
numbered 6