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Botes on flDatbematics.
A Unit is any quantity represented by a single thing, as a
magnitude, or a number regarded as one undivided whole.
Numbers are the measure of the relation between quanti-
ties of things of the same kind and are expressed by figures.
Numbers which are capable of being divided by two without
a remainder are called even numbers. 2, 4, 6, 8, etc., are
even numbers.
Numbers which are not capable of division by two without
giving a remainder are called odd numbers. 1, 3, 5, 7, 9, etc..
are odd numbers.
A number which can not be divided by any whole number
but itself and the number 1 without giving a remainder is
called a prime number. 1, 2, 3, 5, 7, 11, 13, 17, 19, etc., are
prime numbers.
All numbers that are not prime are said to be composite
nwnbers, because they are composed of two or more factors
;
4, 6, 8, 9, 10, 12, etc., are composite numbers.
Whole numbers are called integers. Whole numbers are
also called integral numbers.
A mixed number is the sum of a whole number and a
fraction.
The least common multiple of several given numbers is
the smallest number that can be divided by each without a
remainder. For instance, the least common multiple of 3, 4, 6,
and 5 is 60, because 60 is the smallest number that can be
divided by those numbers without a remainder.
Signs.
+ (plus) is the sign of addition.
— (minus or less) is the sign of subtraction.
The signs 4- and — are also used to indicate positive and
negative quantities.
X (times or multiply) is the sign of multiplication, but in-
stead of this sign, sometimes a single point (.) is used, especially
in formulas: in algebraic expressions very frequently factors
are written without any signs at all between them. For in-
stance, aXb or a.b or ab. All these three expressions indicate
that the quantity a is to be multiplied by the quantity b.
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