Elementary arithmetic, with brief notices of its history... by Robert Potts.

8
The sum of 5 cand I is 6G The sum of 6 and 1 is 7

The sum of 4 and 1 is 5

3 I
9>,2
9~
f),,,,?,
s,
The sum of,,
y,,,,,,
I >

2,, 6
3,, 7
4,, 8
5,, 9
6,, 10
7,, 11
8,, 12
9,, 13
7 and I is 8
2,, 9
3,, 10
4,, 11
5,, 12
6,, 13
7,, 14
8,, 15
9,, 16.,1
5~
~'9
a,
3,
9,
3,
21~
f11,,,
J I
Th s I f n
I I
V, I
I
I I
I5I

3., 8
4,, 9
3,, 8
5,, 10
6., 11
7,, 12
8,, 13
9,, 14
1 is 9
2,, 10
3,, 11
4, 12
5, 13
6,, 14
7,, 15
8,, 16
97, 17

2,, 8,, 3,, 9
4,, 10
5,,I
5,, 12,, 12,,, 13
8, 14
9,,15
The sum of 9 and 1 is 10
2,,11
3,, 12
4,, 13,, 5,, 14, 6,,15,, 7,, ]6
8,,17
9,, 18

3. PROB. To find tlie sum of two nmzbers consisting of more than one
figure.
Ax. The sum of two or more numbers is equal to the sums of their
respective parts taken together.
By the assumed notation every number is composecl of units of the
first, second, or third, &c., orders, named units, tens, hundreds, &c.
And the sum of two or more numbers will be known by finding the
sums of the units, the tens, the hundreds, and so on, and the aggregate of these sums will be the sum of the given numbers.
Let it be required to find the sum of two numbers, 358 and 287.
The number 358 consists of 3 hundreds, 5 tens, and 8 units,
and 287 consists of 2 hundreds, 8 tens, and 7 units.
Then, first, the sum of 7 units and 8 units is 15 units; or 1 ten and
5 units: reserve the 5 units.
Secondly. The sum of 1 ten, 8 tens, and 5 tens, is 14 tens; or 10
tens and 4 tens; or 1 hundred, and 4 tens: reserve the 4 tens.
Thirdly. The sum of 1 hundred, 2 hundreds, and 3 hundreds, is 6
hundreds.
Hence, the whole sum is 6 hundreds, 4 tens, and 5 units, or 645.
The process may be exhibited briefly, thus:358
287

645 sum.
The sum of more numbers than two can be found in the same
manner as the sum of two numbers.1

1 When the columns of numbers to be added are large, the process of addition
may be more easily effected by a method analogous to addition by counters. It relieves
the memory from recollecting any number greater than 19; at the same time there is