by Lucas de Burgo, and publifhed at Venice, 
in the year 1494. You will be infinitely 
pleafed and aftonifhed at the power of this 
Science, when you become perfectly ac- 
quainted with its ufe. I am in this letter, 
fpeaking only of the various modes of Ad- 
dition, viz. of figures as fymbols of whole 
numbers, of vulgar fractions, of decimal 
fractions, and of letters as fymbols of num- 
ber or quantity. 
But, before we proceed with the addition 
of thefe Algebraic quantities, I muft tell 
you, that Algebraifts fuppofe every quantity, 
or letter, to be either pofitive, of which this 
+ is their fign; or negative, which they 
mark thus . The firft they read plus y the 
other minus. You muft alfo remember, that 
when there is no fign prefixed, plus is always 
underftood, and that when there is no figure 
before the letter or quantity, the figure i is 
fuppofed. 
(i) (2) (3) (4) 
To3# To b To gx To + ^y 
Add a Add 2^ Add + i2,v Add gy 
Sum 40 3^ +3* zy 
* 3 (S) 
