Business logic

Write business rules with functions and conditions.

Business logic: compute the average

In this lesson you will compute the average of the grades. sum(grades) gives the total, len(grades) the count; division yields the average:

average = sum(grades) / len(grades)
print("ortalama:", average)
# ortalama: 87.0

The starting code includes the previous lessons' solutions. You will add the average calculation and print. Since grades is now [85, 90, 78, 95], the average is 87.0.

This is the fundamental way to summarise data.

Exercise Compute and print the average

Write average = sum(grades) / len(grades). Then write print("ortalama:", average).

Show example solution

grades = [85, 90, 78]
print(grades)
grades.append(95)
print("eklendi:", len(grades))
average = sum(grades) / len(grades)
print("ortalama:", average)

Next step: error handling

The business logic is ready — you can compute the average. But what if the grades list is empty? len([]) is zero and division by zero raises ZeroDivisionError. In the next lesson you will guard against this with try/except.

This layer will let the app handle error cases without crashing. Robust code anticipates errors and is prepared for them. Each lesson builds on top of the previous one.

Test yourself

How is the average computed?
- sum(grades) * len(grades)
- sum(grades) - len(grades)
- len(grades) / sum(grades)
- sum(grades) / len(grades)
Show answer

sum(grades) / len(grades) — Average = total / count. sum(grades) / len(grades).
Match business logic

sum(grades)

Total
len(grades)

Count
/

Division
average

Result variable

Complete the average calculation

average = ____ / len(grades)

Show answer

average = sum(grades) / len(grades)

Next lesson: Error handling

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