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# Different by One

In the original example, the lines were made from rods that differed in length by 2:

light green rods (3) and yellow rods (5).

You could start by creating lines made from

Which pairs can be used to create lines that differ by 1?## You may also like

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Age 14 to 16

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In the original example, the lines were made from rods that differed in length by 2:

light green rods (3) and yellow rods (5).

You could start by creating lines made from

pink (4) and dark green (6)

yellow (5) and black (7)

yellow (5) and black (7)

dark green (6) and brown (8)

black (7) and blue (9)...

black (7) and blue (9)...

Which pairs can be used to create lines that differ by 1?

Take any pair of two digit numbers x=ab and y=cd where, without loss of generality, ab > cd . Form two 4 digit numbers r=abcd and s=cdab and calculate: {r^2 - s^2} /{x^2 - y^2}.