Euclid

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. First, to master the Preliminary Algebra,' and not to go further until he finds that, when covering up the right-hand column and setting himself any question in the left-hand column, he can at once work out (not merely supply from memory) the required answer.