Question

Ordinal Numbers: Ordinal numbers indicate their position in a list, such as \(1 s t\) or \(2 n d\). Most ordinal numbers end in \(t h\), except 1,2 , and \(3 .\) \- Store the numbers 1 through 9 in a list. \- Loop through the list. \- Use an if-elif-else chain inside the loop to print the proper ordinal ending for each number. Your output should read "1st 2 nd \(3 r d\) 4th 5 th 6 th 7 th 8 th 9 th", and each result should be on a separate line.

Short answer

Loop through numbers using if-elif-else to add correct ordinal endings ('st', 'nd', 'rd', 'th') and print each on separate lines.

Step-by-step solution

Create a List

First, we need to store the numbers 1 through 9 in a list. In Python, this can be done by using the list notation. We can write: ```python numbers = list(range(1, 10)) ``` This will create a list of numbers from 1 to 9 inclusive.

Start Looping Through the List

Now, we need to loop through each element in the list. We will use a `for` loop to iterate over each number. The basic structure will look like this: ```python for number in numbers: # Process each number ```

Use if-elif-else to Determine Ordinal Endings

Within the loop, we'll use an `if-elif-else` structure to check each number and print the correct ordinal ending. We know the following rules: - `1` should end with 'st' - `2` should end with 'nd' - `3` should end with 'rd' - All other numbers should end with 'th' This can be implemented as: ```python for number in numbers: if number == 1: print(f"{number}st") elif number == 2: print(f"{number}nd") elif number == 3: print(f"{number}rd") else: print(f"{number}th") ```

Final Check and Run the Code

Finally, ensure that the loop runs correctly and prints each ordinal on a separate line. Run the code to verify: ```python numbers = list(range(1, 10)) for number in numbers: if number == 1: print(f"{number}st") elif number == 2: print(f"{number}nd") elif number == 3: print(f"{number}rd") else: print(f"{number}th") ``` Each number should now be printed with its correct ordinal ending, one per line.

Key concepts

Ordinal Numbers

Ordinal numbers are numbers that denote position or order in a sequence, offering a way to mark where items fall in a lineup. For example, "1st" indicates the first position, "2nd" for second, and so forth. Generally, ordinal numbers are a straightforward concept:

• "1" becomes "1st"
• "2" becomes "2nd"
• "3" turns into "3rd"
• All other numbers, such as "4", "5", "6", end in "th" like "4th", "5th", "6th"

Understanding the proper use of ordinal numbers is essential because they are frequently used in various contexts, such as dates (June 1st), rankings, and instructions. In programming, generating lists of items that need to be denoted by position often require converting standard numbers into ordinal form.

Conditional Statements

In Python programming, conditional statements are used to make decisions in your code. They allow your program to execute different actions based on specific conditions. The main types of conditional statements are:

• If Statement: Checks whether a condition is true and executes a block of code if it is.
• Elif Statement: Used when you have multiple conditions to check. It stands for "else if" and allows you to test additional conditions if the initial if statement is false.
• Else Statement: Runs a block of code when all preceding conditions are false.

Within the context of the ordinal numbers problem, conditional statements are used to determine the correct suffix for each number. The program evaluates each number and assigns the appropriate suffix based on its value. The logic follows a sequence of "if-elif-else" statements that ensure the correct ordinal representation is printed:

• "1" maps to "st"
• "2" maps to "nd"
• "3" maps to "rd"
• Anything else defaults to "th"

This conditional flow is instrumental in controlling the behavior of the code as it processes through each number in the list.

Looping in Python

Looping is a fundamental programming concept allowing repeated execution of a block of code, often over elements in a sequence like a list or array. Python provides several looping constructs, with the for loop being one of the most commonly used. In the case of generating ordinal numbers, a for loop is used to iterate over the list of numbers from 1 to 9. This type of loop works especially well when you know the number of iterations in advance. The basic structure of a for loop in Python is: ```python for element in sequence: # perform operation ``` Here's how it applies to our ordinal number exercise:

• The loop starts by creating a list of numbers using numbers = list(range(1, 10)).
• Then, the for loop iterates over each number in the list with for number in numbers:.
• Inside the loop, conditional statements determine the ordinal suffix based on the number's value.

These iterations allow us to execute a block of code repeatedly, which is helpful for tasks that require applying the same operation to each item in a collection. This makes looping a powerful and essential tool in any programmer's toolkit.