Find the sum of all numbers between 200 and 400 which are divisible by 7.

Explanation

To find the sum of all numbers between 200 and 400 that are divisible by 7, we can follow these steps:

### Step 1: Identify the first and last terms
First, we need to find the smallest number greater than or equal to 200 that is divisible by 7. We can do this by dividing 200 by 7 and rounding up to the nearest whole number.

\[ \text{First term} (a) = 7 \times \lceil \frac{200}{7} \rceil = 7 \times 29 = 203 \]
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