Let's analyze each of the given addition problems step-by-step to identify which is an error of addition by one.
### Step-by-step Analysis:
#### A. [tex]\(63,528 + 24,361 = 87,889\)[/tex]
The actual result of [tex]\(63,528 + 24,361\)[/tex] is [tex]\(87,889\)[/tex].
This equation is correct.
#### B. [tex]\(27,465 + 52,534 = 79,899\)[/tex]
The actual result of [tex]\(27,465 + 52,534\)[/tex] is [tex]\(79,999\)[/tex].
Since [tex]\(79,999 - 79,899 = 100\)[/tex], this equation is incorrect by an error of 100, not one.
#### C. [tex]\(51,824 + 48,165 = 99,989\)[/tex]
The actual result of [tex]\(51,824 + 48,165\)[/tex] is [tex]\(99,989\)[/tex].
This equation is correct.
#### D. [tex]\(35,246 + 43,732 = 78,978\)[/tex]
The actual result of [tex]\(35,246 + 43,732\)[/tex] is [tex]\(78,978\)[/tex].
This equation is correct.
### Conclusion:
After reviewing each example, we see that each equation is either correct or has an error greater than one. However, only [tex]\(79,899\)[/tex] differs significantly from its actual sum [tex]\(79,999\)[/tex], but the error is [tex]\(100\)[/tex], not [tex]\(1\)[/tex]. Hence, none of these are an error of addition by one.
Based on this analysis, none of the given examples are an error of addition by one.
