( 82 ) 
they tell us, in the prefent cafe, that the 25 
and 75 are parts of a hundred. Knowing 
therefore what they are, I can add them, 
fubtrac"l them one from the other, or work 
with them in any manner I pleafe, juft as 
I would with whole numbers. But before 
I difcover to you what I am about, another 
previous ftep is necefTary. 
Imagine that I have before me the frac- 
tion -i. I want to exprefs its value by a fin- 
gle figure, without this troublefome deno- 
minator. I know that I can multiply thefe 
two figures feparately by any other figure 
without altering their value, thus multiply- 
ing them by 5, the i becomes a 5 and the 2 
a i o : the fraction therefore is now T V or 
-/A or -AAAr. I now perceive that I have 
no farther occafion for thefe denominators ; 
that in thefe Decimal Fractions one figure 
denotes tenths, two figures hundredths, three 
figures thoufandths: thus ,4 with a comma 
before it, fignifies four parts of ten; ,37 
means thirty feven parts of a hundred ; ,365, 
are three hundred and fixty five parts of a 
thoufand. This being perfectly underftood, 
I can add thefe Decimals in the fame man- 
ner as whole numbers. For example, 
To 
