NOTATION - . 
or 8. In like manner a -P b 4- c denotes the number 
arising by adding all the three numbers a, b, and c, 
together. 
Nate. A quantity which has no prefixed sign (as the 
leading quantity a in the above examples) is always un 
derstood to have the sign p before it; so that a signifies 
the same as p a; and a P b, the same as -p a p b. 
The Sign—,signifies that the quantity which it precedes 
is to be subtracted. Thus a— b shews that the quan 
tity represented by b is to be subtracted from that repre 
sented by a, and expresseth the difference of a and b; 
so that, if a was 5, and b 3, then would a — b be 5-*—3, 
or 2. In like manner a -\-b — c — d represents the 
quantity which arises by taking the numbers c and d 
from the sum of the other two numbers a and b ; as if 
a was 7, b 6, c 5, and d 3, then would a -p b — c — d 
be 7 4-6 — 5 — 3, or 5. 
The Notes P and — are usually expressed by the 
words plus (or more) and- minus (or less). Thus, wo 
read, a + b, a plus b; and a — b, a minus b. 
Moreover, those quantities to which the sign -p- is 
prefixed are called positive (or affirmative); and those to 
which the sign — is prefixed, negative. 
The Sign x , signifies that the quantities between ichich 
it sta72ds are to be multiplied together. Thus a x b denotes 
that the quantity a is to be multiplied by the quantity 
and expresses the product of the quantities so multi 
plied; and a x b x c expresses the product arising by 
multiplying the quantities a, b, and c, continually to 
gether: thus, likewise, afi x c denotes the product of 
product which arises by multiplying the three com 
pound quantities a -p b + c, a — b p c, and ape con 
tinually together ; so that, if a was 5, b 4, and c 3, then 
a + c be 12 x 
But when quantities denoted by single letters are to 
be multiplied together, the Sign x is generally omit 
ted, or only understood; and so ab is made to signify 
file- same as a x 6; and abc, the same as a x b x ct