[6] In this and all other processes, the student is strongly recommended to look at and follow the [first Appendix].
[7] Those numbers which have been altered are put in italics.
[8] As it is usual to learn the product of numbers up to 12 times 12, I have extended the table thus far. In my opinion, all pupils who shew a tolerable capacity should slowly commit the products to memory as far as 20 times 20, in the course of their progress through this work.
[9] To speak always in the same way, instead of saying that 6 does not contain 13, I say that it contains it 0 times and 6 over, which is merely saying that 6 is 6 more than nothing.
[10] If you have any doubt as to this expression, recollect that it means “contains more than two eighteens, but not so much as three.”
[11] Among the even figures we include 0.
[12] Including both ciphers and others.
[13] For shortness, I abbreviate the words greatest common measure into their initial letters, g. c. m.
[14] Numbers which contain an exact number of units, such as 5, 7, 100, &c., are called whole numbers or integers, when we wish to distinguish them from fractions.
[15] A factor of a number is a number which divides it without remainder: thus, 4, 6, 8, are factors of 24, and 6 × 4, 8 × 3, 2 × 2 × 2 × 3, are several ways of decomposing 24 into factors.