## Hexagonal Squares

The square numbers \((1, 4, 9, 16, 25, \ldots\) are the numbers which can be arranged to make a square array of dots. Analogously, the Hexagonal numbers \((1, 7, 19, 37, \ldots\) are the numbers which can be arranged to make a hexagonal array of dots. A "Hexagonal-Square" is any positive integer which is both a Hexagonal number and a Square number. So for example \(1\) is the first (smallest) Hexagonal-Square.

Part A | What is the second Hexagonal-Square? | |
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Part B | What is the sum of the first \(6\) Hexagonal-Squares? | |

Part C | What is the square root of the tenth Hexagonal-Square? |