Complete the Arithmetic Sequence: From 20 to 2 in Chair Numbers

To solve this problem, we'll follow these steps:

• Step 1: Identify the common pattern or rule in the sequence.
• Step 2: Use this pattern to determine the missing numbers.
• Step 3: Verify the pattern continues correctly with the numbers found.

Now, let's work through each step:
Step 1: The sequence provided is 20, 18, 16, 14, __, __, 8, 6, 4, 2.
We notice that each number differs from the previous one by $-2$ (20 to 18, 18 to 16, etc.). This suggests an arithmetic sequence with a common difference of $-2$.

Step 2: Let's continue this pattern to find the missing numbers. We have 16, 14, and then the blank spaces before reaching 8. So, following the pattern:
From 14, subtract 2 to get 12.
From 12, subtract 2 to get 10.
So, the missing numbers in the sequence are 12 and 10.

Step 3: Verify the sequence by checking the pattern:
Starting from 20: 20, 18, 16, 14, 12, 10, 8, 6, 4, 2.
Each step follows the pattern of subtracting 2.

Therefore, the missing numbers in the series are $12, 10$.