To change a silver rectangle into a golden rectangle and by folding demonstrate the equation X=(sqr5-1)/2

1) Fold the short side over to lay along the long side, make a nick to mark the size of a square. fold the short side down to the mark, make a crease forming half a square. Put in the diagonal in this half square.

2) Fold the right edge over to the diagonal. According to Pythagoras, the diagonal in a half square is sqr5..

3) Fold the upper left down to the diagonal, thereby deducting 1 from sqr5 and mark the place.

4) fold the right corner over to the mark, thereby dividing the rest of sqr5 in 2, and you have found X. as in------------

5) Open all folds and study the creases.

A4 format has been used in this example.