Commodore PET User Manual page 210

Method 2: Multiple Integer Addition
Another way to overcome the 9-digit length limit during addition is to use
the multiple integer addition method.
Multiple integer math reorganizes a large number into smaller seg-
ments. Each segment is handled independently during the addition. The in-
dividual answers are joined together into one final answer, as demonstrated
below:
Input numbers
I.,r--. . . . . . .
= ~~~
. . . . . . .
h
1
~
High answer
'--"""'("""---1
Low
The steps involved in multiple integer addition are as follows:
1. Input the augend and addend as two positive numeric strings.
2. Divide the number into two equal parts of high, low.
3. Calculate the sums of high-order digits and low-order digits.
4. Concatenate the sums into one answer string.
5. Print the answer string.
Step 1: Input the augend and addend as two positive numbers in
numeric string mode:
le PR I NT
Il
::lt!••
MUL
TI PLE I NTEGER ADD I T I Ot~:+::+i.
Il :
PI': I tH
2(1
INPUT A$, B$
RUN
.:+i:+:MULTIPLE INTEGER ADDITION•••
?1234567890123456
??57943572
A$ is the augend and B$ is the addend. The numbers are input as numeric strings
because: 1) the numeric length limit is avoided and 2) it allows use of string
functions to divide the numbers into small segments.
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