During a visit to an ancient temple, students discovered a stone tablet engraved with a \(3 \times 3\) number grid. The guide explained that it was a magic square, where every row, every column, and both diagonals have the same total. However, years of weathering had erased one of the numbers. The students decided to use the properties of a magic square to restore the missing value instead of guessing.
Magic square:
| 8 | 1 | 6 |
| 3 | 5 | \(x\) |
| 4 | 9 |
2
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(i) Which property confirms that this is a magic square?
(ii) What number should replace \(x\)?
(iii) If 4 is added across all the cells, then what will be the magic sum?
(iv) If quadrupling each term in the magic square, then what will be the centre number?