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# Triangular Numbers

Pro Problems > Math > Number and Quantity > Number Theory > Patterns

## Triangular Numbers

A triangular number is a number which can be represented by a set of dots drawn in a triangular pattern. For example, ten is a triangular number because it can be displayed like this:

```♦ ♦ ♦ ♦
♦ ♦ ♦
♦ ♦
♦
```

Thus, the first few triangular numbers are 1, 3, 6, 10, and 15. Find the 200th triangular number.

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Problem by Mr. Twitchell

## Solution

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