Page:Euclid's Elements 1714 Barrow translation.djvu/154

142 X. A number oddly odd is that which an odd number meaures by an odd number.

XI. A prime (or fir) number is that, which is meaured only by an unit.

XII. Numbers prime the one to the other, are uch as only an unit doth meaure, being their common meaure.

XIII. A compoed number is that which ome certain number meaures.

XIV. Numbers compoed the one to the other, are they, which ome number, being a common meaure to them both, does mcaure.

In this, and the preceding definition, unity is not a number.

XV. One number is aid to multiply another, when the number multiplied is o often added to itelf, as there are units in the number multiplying, and another number is produced.

Hence in every multiplication a unit is to the multiplier, as the multiplicand is to the product.

Ob. That many times, when any number are to be multiplied as (A into B) the conjunction of the letters denotes the product: So AB=A×B, and CDE=C×D×E.

XVI. When two numbers multiplying themelves produce another, the number produced is called a plain number; and the numbers which multiplied one another, are called the ides of that number: So 2(C)×3(D)=6=CD is a plain number.

XVII. But when three numbers multiplying one another produce any number, the number produced is termed a olid number; and the numbers multiplying one another, are the ides thereof: So 2(C)x3(D)x5(E)=30=CDE is a olid number.

XVIII. A quare number is that which is equally equal; or, which is contained under two equal numbers. ''Let A be the ide of a quare; the quare is thus noted, AA, or Aq. or A².''

XIX. A