21 + 6 + 9

21 + 6 + 9 = 36

To add 21, 6, and 9 together, follow these steps:

Step 1: Start with the first two numbers, 21 and 6
Step 2: Add 21 and 6 together: 21 + 6 = 27
Step 3: Take the sum from step 2, which is 27, and add the third number, which is 9
Step 4: Add 27 and 9 together: 27 + 9 = 36

Therefore, 21 + 6 + 9 equals 36.