( 79 ) 
than the number of units lefs than ten. 
The number of tens evidently belongs to the 
next column on the left hand j for, fuppofe 
I am adding the fecond column from the 
right, though I do nothing more than add 
units together, yet, occupying the fecond 
place, they are tens. In like manner,' every 
ten in the third column is ten hundred, and 
muft therefore be carried to the fourth co- 
lumn, the column of thoufands, and fo on. 
Thus far we are carried along by the 
ftream, without the lead trouble. Let us 
now confider the 25 and 75 as fractional 
parts of 100. In plainer terms, let us fup- 
pofe a rod of any length you pleafe, broken 
into a hundred pieces ; thefe pieces are pro- 
perly called broken, or fractional, parts of 
a hundred. But 25 being one fourth part 
of 100, and 75 being three quarters of 100, 
they might be thus written -J- and ^. How 
are thefe two fractions to be added fo as to 
make a hundred? The figure above the 
line is called the numerator , becaufe it indi- 
cates the number of parts, and the figure 
below the line is called the denominator^ be- 
caufe it denominates the kind of parts. In 
thefe two fractions they are both of the fame 
denomination, both fourths: therefore, in 
the 
