Editing Magic square (section)

===A method for constructing a magic square of order 3===
In the 19th century, [[Édouard Lucas]] devised the general formula for order 3 magic squares. Consider the following table made up of positive integers ''a'', ''b'' and ''c'':
{| class="wikitable" style="margin-left:auto;margin-right:auto;text-align:center;width:26em;height:6em;table-layout:fixed;"
|-
| ''c'' &minus; ''b'' || ''c'' + (''a'' + ''b'') || ''c'' &minus; ''a''
|-
| ''c'' &minus; (''a'' &minus; ''b'') || ''c'' || ''c'' + (''a'' &minus; ''b'')
|-
| ''c'' + ''a'' || ''c'' &minus; (''a'' + ''b'') || ''c'' + ''b''
|}
These nine numbers will be distinct positive integers forming a magic square with the magic constant 3''c'' so long as 0 < ''a'' < ''b'' < ''c'' &minus; ''a'' and ''b'' ≠ 2''a''. Moreover, every 3×3 magic square of distinct positive integers is of this form.

In 1997 [[Lee Sallows]] discovered that leaving aside rotations and reflections, then every distinct [[parallelogram]] drawn on the [[Argand diagram]] defines a unique 3×3 magic square, and vice versa, a result that had never previously been noted.<ref name=lost-theorem/>