The largest number in a set of odd numbers can be determined by following a few simple steps. Let's break down the process.

Step 1: Understand odd numbers
Odd numbers are integers that cannot be divided evenly by 2. They are always one more than an even number. For example, 3, 5, 7, 9, etc., are all odd numbers.

Step 2: Identify the largest odd number
To find the largest number in a set of odd numbers, you need to compare the values of each number in the set. Here's how you can do it:

- Start by listing all the odd numbers in the set.
- Compare the first number with the second number. If the first number is larger, keep it as the temporary largest number. If the second number is larger, replace the temporary largest number with the second number.
- Continue comparing the temporary largest number with the next number in the set. If the next number is larger, replace the temporary largest number with the new number.
- Repeat this process until you have compared all the numbers in the set.
- At the end, the temporary largest number will be the largest odd number in the set.

Example:
Let's take a set of odd numbers: 23, 11, 17, 29, 15, 21.

- Start with the first number, 23, as the temporary largest number.
- Compare it with the next number, 11. Since 23 is larger than 11, keep 23 as the temporary largest number.
- Compare 23 with the next number, 17. Again, 23 is larger, so it remains the temporary largest number.
- Next, compare 23 with 29. This time, 29 is larger, so replace 23 with 29 as the temporary largest number.
- Continue comparing 29 with the remaining numbers. 29 is larger than both 15 and 21, so it remains the temporary largest number.
- Finally, we have compared all the numbers, and the temporary largest number, 29, is the largest odd number in the set.

Therefore, the largest number in the given set of odd numbers (23, 11, 17, 29, 15, 21) is 29.