(1) Reduce .

255 = 9 × 27 + 12

27 = 2 × 12 + 3

12 = 4 × 3

Therefore 3
is the least common divisor and so

(2) Reduce .

2268 = 3 × 594 + 486

594 = 1 × 486 + 108

486 = 4 × 108 + 54

108 = 2 × 54

Therefore
54 is the least common divisor and so .

In this
second example, Macdonald only got as far as .