How to Write a Python Code to Print Numbers from 1 to 100 Excluding Multiples of 3 and 5

This tutorial will guide you through the process of writing a Python program to print all numbers from 1 to 100, excluding multiples of 3 and 5. This is a common problem assigned in early programming courses and forms a fundamental basis for solving more complex problem statements.

Understanding the Problem

The problem involves generating a list of numbers from 1 to 100 and excluding those that are multiples of 3 and 5. This can be achieved through a loop or by generating the list directly. We'll explore both methods and discuss the efficiency and readability of each.

Method 1: Using a Loop

The loop method involves iterating through each number from 1 to 100 and checking if it is a multiple of 3 or 5. If it is not, we print it. This is a simple and straightforward approach.

Python Code Example:

for i in range(1, 101):
    if i % 3 ! 0 and i % 5 ! 0:
        print(i)

Method 2: Using List Comprehension

List comprehension is a more compact and Pythonic way to achieve the same result. We generate a list of all numbers from 1 to 100 and then filter out the multiples of 3 and 5.

Python Code Example:

print([i for i in range(1, 101) if i % 3 ! 0 and i % 5 ! 0])

Additional Tips and Tricks

Understanding the behavior of the modulo operator is crucial. The modulo operator (%) returns the remainder of the division of the number by 3 or 5. If the remainder is 0, the number is a multiple of 3 or 5.

Tips for Humans: Multiples of 5 end in 0 or 5, but in Python, use the modulo operator to check divisibility. If the sum of the digits of a number is divisible by 3, the number is divisible by 3, but this is not a programming technique.

Avoiding Repetitive Printing

If you want to save the output to a variable or file, you can modify the loop to do so. Here's an example:

exclude_dict  {1, 2, 4, 7, 8, 11, 13, 14, 16, 17, 19, ...}
while exclude_dict:
    i  exclude_dict.pop()
    print(i)

Class Assignment and Practice

Since this is a common assignment, your professor might be expecting you to fill in the missing parts of the code provided in the class assignment. Here's what you can do:

def classAssignment():
    print(1)
    print(2)
    print(4)
    print(7)
    print(8)
    print(11)
    print(13)
    print(14)
    print(16)
    print(17)
    print(19)
    ... # Continue the sequence up to 100

Your professor will surely be impressed with your programming skills and may share your solution with the rest of the class.

Conclusion

Mastering the basics of Python coding, such as loops and list comprehensions, is crucial for solving more complex problem statements. Practice regularly and you will find that programming becomes less daunting over time.