If the sum of first `n` even natural numbers is 420, find the value of `ndot`

Explanation

To solve the problem of finding the value of \( n \) such that the sum of the first \( n \) even natural numbers is 420, we can follow these steps:

### Step 1: Understand the series of even natural numbers
The first \( n \) even natural numbers can be represented as:
\[ 2, 4, 6, \ldots, 2n \]

### Step 2: Use the formula for the sum of an arithmetic series
The sum \( S_n \) of the first \( n \) even natural numbers can be calculated using the formula for the sum of an arithmetic series:
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