# Page:Philosophical Transactions - Volume 096.djvu/383

The chief part of the working consists in merely setting down a number under itself removed one or more places to the right, and subtracting, and repeating this operation; and consequently is very little liable to mistake. Moreover, from e commodious manner in which the work stands, it may be revised with extreme rapidity. It may be performed after a few minutes instruction by any one who is competent to subtract. It is as easy for large numbers as for small; and on an average about 27 subtractions will furnish a logarithm acccurately to 10 places of decimals. In general ${\displaystyle 9\times {\frac {n+1}{2}}}$ subtractions will be accurate to ${\displaystyle 2n}$ places of decimals.
In computing hyperbolic logarithms by this method it is necessary to have previously establised the h. logs. of ${\displaystyle {\frac {10}{9}},{\frac {100}{99}},{\frac {1000}{999}},}$ &c. of 2 and of 10.