1) (1/2)-(1/3) = (3/6)-(2/6) = (1/6)
2)(1/3)-(1/4) = (4/12) - (3/12) = (1/12)
(1/6)-(1/7) = (7/42)-(6/42) = (1/42)
3)(1/4)-(1/5) = (5/20)-(4/20) = (1/20)
(1/5)-(1/6) = (6/30)-(5/30) = (1/30)
(1/7)-(1/8) = (8/56)-(7/56) = (1/56)
(1/8)-(1/9) = (9/72)-(8/72) = (1/72)
(1/9)-(1/10) = (10/90)-(9/90) = (1/90)
4) on fait (1/(10×11)) et on obtient le resultat
5) avec (1/81) et (1/82) = (1/81×82) = (1/6642)