Division

Fujimoto's method for marking one third in a square.

Left diagram. Mark diagonal, fold b

Bottom edge along diagonal and mark at A

Right diagram. Fold C to A and mark at M, this gives one third of top edge.

FUJIMOTO'S METHOD OF ESTIMATING A FIFTH AND TWO SEVENTHS OF A SQUARE

The methods below depend on the fact that the ratio of the diagonal of a square to
its side is within about one percent of the ratio of 7 to 5. For many purposes this may
accurate enough, otherwise the methods give an excellent starting point for Fujimoto's
convergent methods. In practice only marks are needed in any fold.

Estimating one fifth.

Left diagram, mark diagonal and centre line. Right diagram, fold bottom edge to centre line and mark at M, this gives an approximate one fifth point.

Estimating two sevenths

Left diagram. Mark both diagonals. Right diagram. Put bottom edge along diagonal and mark S. This gives two sevenths up the diagonal (approx).