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A316. SVP 7 ou plus, rien d'autre

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A316. SVP 7 ou plus, rien d'autre

Démontrer qu’il existe une infinité de couples d’entiers naturels tels que chacun d’eux et leur produit contiennent exclusivement des chiffres supérieurs ou égaux à 7.

1. Un (premier) couple de base et la démonstration Soient ܽ

et ܾ

ܽ

= 8. 10

௡ିଵ

+ 7

9 ሺ10

௡ିଵ

− 1ሻ

ܾ

= 8. 10

௡ିଵ

+ ሺ10

௡ିଷ

− 1ሻ. 10

+ 87

ܽ

s’écrit avec le chiffre 8 suivi de ݊ − 1 chiffres 7 ( ܽ

= 877777 )

ܾ

s’écrit avec le chiffre 8 suivi de ݊ − 3 chiffres 9 puis 8 et 7 ( ܾ

= 899987 ) On va montrer que le produit ܽ

. ܾ

= ܿ

s’écrit avec seulement de 7, des 8 et des 9.

ܿ

= ܽ

. ܾ

ሺ8. 10௡ିଵሻ. ሺ8. 10௡ିଵሻ +ሺ8. 10௡ିଵሻ. ሺ10௡ିଷ− 1ሻ. 10 +ሺ8. 10௡ିଵሻ. 87 +7

9 ሺ10௡ିଵ− 1ሻ. 8. 10௡ିଵ +7

9 ሺ10௡ିଵ− 1ሻ. ሺ10௡ିଷ− 1ሻ. 10 +7

9 ሺ10௡ିଵ− 1ሻ. 87 +64. 10ଶ௡ିଶ +8. 10ଶ௡ିଶ− 8. 10௡ାଵ +696. 10௡ିଵ +56

9 10ଶ௡ିଶ−56

9 10௡ିଵ +7

9 10ଶ௡ିଶ−7

9 10௡ାଵ−7

9 10௡ିଵ+7

9 10 +609

9 10௡ିଵ−609 9

Termes en 2n-2 Termes en n+1 Termes en n-1 Termes constants

64. 10ଶ௡ିଶ+ 8. 10ଶ௡ିଶ+56

9 10ଶ௡ିଶ+7

9 10ଶ௡ିଶ −8. 10௡ାଵ−7 9 10௡ାଵ

+696. 10௡ିଵ−56

9 10௡ିଵ−7 9 10௡ିଵ +609

9 10௡ିଵ

+7

9 10−609 9 ൬64 + 8 +56

9 + 7

9൰ . 10ଶ௡ିଶ ൬−8 −7

9൰ 10௡ାଵ ൬696 −56 9 −

7 9 +

609 9 ൰ 10௡ିଵ

91 9

79. 10ଶ௡ିଶ −79

9 10௡ାଵ

6810 9 10௡ିଵ 79. 10ଶ௡ିଶ−10ଶ௡ିଶ +10ଶ௡ିଶ−79

9 10௡ାଵ

681 9 10

78. 10ଶ௡ିଶ ൬10௡ିସ−79

90൰ 10௡ାଶ ൬10௡ିସ−79

90−11

90൰ 10௡ାଶ 681 9 10+11

90 10௡ାଶ

ሺ10௡ିସ− 1ሻ10௡ାଶ 791

9 10 791

9 10−8

9 10 +8

9 10

87.10 +8

9 10−800

9 +800

9 +91 9 +800

9 10௡ିଶ−800 8 9

9 ሺ10௡ିଶ− 1ሻ10 99

ܿ

= ܽ

. ܾ

= 78. 10

ଶ௡ିଶ

+ ሺ10

௡ିସ

− 1ሻ10

௡ାଶ

+ 87.10

+ 8

9 ሺ10

௡ିଶ

− 1ሻ10

+ 99

ܿ

commence par 78, suivi de ݊ − 4 chiffres 9, puis 87, suivi de ݊ − 2 chiffres 8, et se termine par 99.

ܿ

= 789 987 888 899

݊

ܽ ܾ

ܿ

= ܽ

. ܾ

3 877 887 777899

4 8777 8987 78878899

5 87777 89987 7898788899

6 877777 899987 789987888899

7 8777777 8999987 78999878888899 8 87777777 89999987 7899998788888899 9 877777777 899999987 789999987888888899 10 8777777777 8999999987 78999999878888888899

(2)

2. Le deuxième un peu différent avec ܽ

= constante

ܽ

= 8877

ܾ

= 8887 10

ସ௡

− 1 10

− 1

ܿ

= 7 889. 10

ସ௡

+ 7 788 10

ସሺ௡ିଶሻ

− 1

10

− 1 10

+ 77 879 899 et on a bien ∶ ܽ

. ܾ

= ܿ

1 8 877 8887 7888 9899 ok

2 8 877 8887 8887 7889 7787 9899 ok

3 8 877 8887 8887 8887 7889 7788 7787 9899 ok

4 8 877 8887 8887 8887 8887 7889 7788 7788 7787 9899 ok

5 8 877 8887 8887 8887 8887 8887 7889 7788 7788 7788 7787 9899 ok

6 8 877 8887 8887 8887 8887 8887 8887 7889 7788 7788 7788 7788 7787 9899 ok

7 8 877 8887 8887 8887 8887 8887 8887 8887 7889 7788 7788 7788 7788 7788 7787 9899 ok

8 8 877 8887 8887 8887 8887 8887 8887 8887 8887 7889 7788 7788 7788 7788 7788 7788 7787 9899 ok

9 8 877 8887 8887 8887 8887 8887 8887 8887 8887 8887 7889 7788 7788 7788 7788 7788 7788 7788 7787 9899 ok 10 8 877 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 7889 7788 7788 7788 7788 7788 7788 7788 7788 7787 9899 ok 11 8 877 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 7889 7788 7788 7788 7788 7788 7788 7788 7788 7788 7787 9899 ok 12 8 877 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 7889 7788 7788 7788 7788 7788 7788 7788 7788 7788 7788 7787 9899 ok 13 8 877 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 8887 7889 7788 7788 7788 7788 7788 7788 7788 7788 7788 7788 7788 7787 9899 ok

3. La démonstration, ainsi que celles des couples suivants, doit être identique à celle déjà effectuée.

݌݋ݑݎ ݊ ≥ 3

൬8

9 ሺ10− 1ሻ. 10 + 7൰൫ሺ10௡ିଷ− 1ሻ. 10+ 8877൯

= 8

9 ሺ10

௡ିଷ

− 1ሻ. 10

௡ାହ

+ 7888. 10

௡ାଵ

+ 7

9 ሺ10

௡ିଷ

− 1ሻ. 10

+ 9899

3 8 887 8 877 78 889 899 ok

4 88 887 98 877 8 788 879 899 ok

5 888 887 998 877 887 888 779 899 ok

6 8 888 887 9 998 877 88 878 887 779 899 ok

7 88 888 887 99 998 877 8 888 788 877 779 899 ok

8 888 888 887 999 998 877 888 887 888 777 779 899 ok

9 8 888 888 887 9 999 998 877 88 888 878 887 777 779 899 ok

10 88 888 888 887 99 999 998 877 8 888 888 788 877 777 779 899 ok

11 888 888 888 887 999 999 998 877 888 888 887 888 777 777 779 899 ok

12 8 888 888 888 887 9 999 999 998 877 88 888 888 878 887 777 777 779 899 ok

13 88 888 888 888 887 99 999 999 998 877 8 888 888 888 788 877 777 777 779 899 ok

14 888 888 888 888 887 999 999 999 998 877 888 888 888 887 888 777 777 777 779 899 ok

15 8 888 888 888 888 887 9 999 999 999 998 877 88 888 888 888 878 887 777 777 777 779 899 ok

16 88 888 888 888 888 887 99 999 999 999 998 877 8 888 888 888 888 788 877 777 777 777 779 899 ok 17 888 888 888 888 888 887 999 999 999 999 998 877 888 888 888 888 887 888 777 777 777 777 779 899 ok 18 8 888 888 888 888 888 887 9 999 999 999 999 998 877 88 888 888 888 888 878 887 777 777 777 777 779 899 ok 19 88 888 888 888 888 888 887 99 999 999 999 999 998 877 8 888 888 888 888 888 788 877 777 777 777 777 779 899 ok 20 888 888 888 888 888 888 887 999 999 999 999 999 998 877 888 888 888 888 888 887 888 777 777 777 777 777 779 899 ok 21 8 888 888 888 888 888 888 887 9 999 999 999 999 999 998 877 88 888 888 888 888 888 878 887 777 777 777 777 777 779 899 ok 22 88 888 888 888 888 888 888 887 99 999 999 999 999 999 998 877 8 888 888 888 888 888 888 788 877 777 777 777 777 777 779 899 ok 23 888 888 888 888 888 888 888 887 999 999 999 999 999 999 998 877 888 888 888 888 888 888 887 888 777 777 777 777 777 777 779 899 ok 24 8 888 888 888 888 888 888 888 887 9 999 999 999 999 999 999 998 877 88 888 888 888 888 888 888 878 887 777 777 777 777 777 777 779 899 ok 25 88 888 888 888 888 888 888 888 887 99 999 999 999 999 999 999 998 877 8 888 888 888 888 888 888 888 788 877 777 777 777 777 777 777 779 899 ok

(3)

4.

݌݋ݑݎ ݊ ≥ 6

൬8

9 ሺ10௡ିସ− 1ሻ. 10+ 7987൰൫ሺ10௡ିଷ− 1ሻ. 10+ 777൯

= 8

9 ሺ10

௡ିସ

− 1ሻ. 10

௡ାସ

+ 7788. 10

+ 7

9 ሺ10

௡ି଺

− 1ሻ. 10

+ 978899

6 887 987 999 777 887 788 978 899 ok

7 8 887 987 9 999 777 88 877 887 978 899 ok

8 88 887 987 99 999 777 8 888 778 877 978 899 ok

9 888 887 987 999 999 777 888 887 788 777 978 899 ok

10 8 888 887 987 9 999 999 777 88 888 877 887 777 978 899 ok

11 88 888 887 987 99 999 999 777 8 888 888 778 877 777 978 899 ok

12 888 888 887 987 999 999 999 777 888 888 887 788 777 777 978 899 ok

13 8 888 888 887 987 9 999 999 999 777 88 888 888 877 887 777 777 978 899 ok

14 88 888 888 887 987 99 999 999 999 777 8 888 888 888 778 877 777 777 978 899 ok

15 888 888 888 887 987 999 999 999 999 777 888 888 888 887 788 777 777 777 978 899 ok

16 8 888 888 888 887 987 9 999 999 999 999 777 88 888 888 888 877 887 777 777 777 978 899 ok

17 88 888 888 888 887 987 99 999 999 999 999 777 8 888 888 888 888 778 877 777 777 777 978 899 ok 18 888 888 888 888 887 987 999 999 999 999 999 777 888 888 888 888 887 788 777 777 777 777 978 899 ok 19 8 888 888 888 888 887 987 9 999 999 999 999 999 777 88 888 888 888 888 877 887 777 777 777 777 978 899 ok 20 88 888 888 888 888 887 987 99 999 999 999 999 999 777 8 888 888 888 888 888 778 877 777 777 777 777 978 899 ok 21 888 888 888 888 888 887 987 999 999 999 999 999 999 777 888 888 888 888 888 887 788 777 777 777 777 777 978 899 ok 22 8 888 888 888 888 888 887 987 9 999 999 999 999 999 999 777 88 888 888 888 888 888 877 887 777 777 777 777 777 978 899 ok 23 88 888 888 888 888 888 887 987 99 999 999 999 999 999 999 777 8 888 888 888 888 888 888 778 877 777 777 777 777 777 978 899 ok 24 888 888 888 888 888 888 887 987 999 999 999 999 999 999 999 777 888 888 888 888 888 888 887 788 777 777 777 777 777 777 978 899 ok 25 8 888 888 888 888 888 888 887 987 9 999 999 999 999 999 999 999 777 88 888 888 888 888 888 888 877 887 777 777 777 777 777 777 978 899 ok

5.

݌݋ݑݎ ݊ ≥ 7

൬8

9 ሺ10௡ିଶ− 1ሻ. 10+ 77൰൫ሺ10௡ି଺− 1ሻ. 10+ 898887൯

= 8

9 ሺ10

௡ି଺

− 1ሻ. 10

௡ା଺

+ 798998. 10

+ 7

9 ሺ10

௡ି଻

− 1ሻ. 10

+ 8979899

7 8 888 877 9 898 887 87 989 988 979 899 ok

8 88 888 877 99 898 887 8 879 899 878 979 899 ok

9 888 888 877 999 898 887 888 798 998 778 979 899 ok

10 8 888 888 877 9 999 898 887 88 887 989 987 778 979 899 ok

11 88 888 888 877 99 999 898 887 8 888 879 899 877 778 979 899 ok

12 888 888 888 877 999 999 898 887 888 888 798 998 777 778 979 899 ok

13 8 888 888 888 877 9 999 999 898 887 88 888 887 989 987 777 778 979 899 ok

14 88 888 888 888 877 99 999 999 898 887 8 888 888 879 899 877 777 778 979 899 ok

15 888 888 888 888 877 999 999 999 898 887 888 888 888 798 998 777 777 778 979 899 ok

16 8 888 888 888 888 877 9 999 999 999 898 887 88 888 888 887 989 987 777 777 778 979 899 ok

17 88 888 888 888 888 877 99 999 999 999 898 887 8 888 888 888 879 899 877 777 777 778 979 899 ok 18 888 888 888 888 888 877 999 999 999 999 898 887 888 888 888 888 798 998 777 777 777 778 979 899 ok 19 8 888 888 888 888 888 877 9 999 999 999 999 898 887 88 888 888 888 887 989 987 777 777 777 778 979 899 ok 20 88 888 888 888 888 888 877 99 999 999 999 999 898 887 8 888 888 888 888 879 899 877 777 777 777 778 979 899 ok 21 888 888 888 888 888 888 877 999 999 999 999 999 898 887 888 888 888 888 888 798 998 777 777 777 777 778 979 899 ok 22 8 888 888 888 888 888 888 877 9 999 999 999 999 999 898 887 88 888 888 888 888 887 989 987 777 777 777 777 778 979 899 ok 23 88 888 888 888 888 888 888 877 99 999 999 999 999 999 898 887 8 888 888 888 888 888 879 899 877 777 777 777 777 778 979 899 ok 24 888 888 888 888 888 888 888 877 999 999 999 999 999 999 898 887 888 888 888 888 888 888 798 998 777 777 777 777 777 778 979 899 ok 25 8 888 888 888 888 888 888 888 877 9 999 999 999 999 999 999 898 887 88 888 888 888 888 888 887 989 987 777 777 777 777 777 778 979 899 ok

(4)

݌݋ݑݎ ݊ ≥ 6

ቆ78. 10௡ିଶ+7

9 ሺ10௡ିଶ− 1ሻቇሺ98. 10௡ିଶ+ ሺ10௡ିସ− 1ሻ. 10+ 87ሻ= 7798. 10ଶ௡ିସ+ ሺ10௡ି଺− 1ሻ. 10௡ାଶ+ 889. 10௡ିଵ+8

9 ሺ10௡ିଷ− 1ሻ. 10+ 99

6 787 777 989 987 779 888 988 899 ok

7 7 877 777 9 899 987 77 989 889 888 899 ok

8 78 777 777 98 999 987 7 798 998 898 888 899 ok

9 787 777 777 989 999 987 779 899 988 988 888 899 ok

10 7 877 777 777 9 899 999 987 77 989 999 889 888 888 899 ok

11 78 777 777 777 98 999 999 987 7 798 999 998 898 888 888 899 ok

12 787 777 777 777 989 999 999 987 779 899 999 988 988 888 888 899 ok

13 7 877 777 777 777 9 899 999 999 987 77 989 999 999 889 888 888 888 899 ok

14 78 777 777 777 777 98 999 999 999 987 7 798 999 999 998 898 888 888 888 899 ok

15 787 777 777 777 777 989 999 999 999 987 779 899 999 999 988 988 888 888 888 899 ok

16 7 877 777 777 777 777 9 899 999 999 999 987 77 989 999 999 999 889 888 888 888 888 899 ok

17 78 777 777 777 777 777 98 999 999 999 999 987 7 798 999 999 999 998 898 888 888 888 888 899 ok 18 787 777 777 777 777 777 989 999 999 999 999 987 779 899 999 999 999 988 988 888 888 888 888 899 ok 19 7 877 777 777 777 777 777 9 899 999 999 999 999 987 77 989 999 999 999 999 889 888 888 888 888 888 899 ok 20 78 777 777 777 777 777 777 98 999 999 999 999 999 987 7 798 999 999 999 999 998 898 888 888 888 888 888 899 ok 21 787 777 777 777 777 777 777 989 999 999 999 999 999 987 779 899 999 999 999 999 988 988 888 888 888 888 888 899 ok 22 7 877 777 777 777 777 777 777 9 899 999 999 999 999 999 987 77 989 999 999 999 999 999 889 888 888 888 888 888 888 899 ok 23 78 777 777 777 777 777 777 777 98 999 999 999 999 999 999 987 7 798 999 999 999 999 999 998 898 888 888 888 888 888 888 899 ok 24 787 777 777 777 777 777 777 777 989 999 999 999 999 999 999 987 779 899 999 999 999 999 999 988 988 888 888 888 888 888 888 899 ok 25 7 877 777 777 777 777 777 777 777 9 899 999 999 999 999 999 999 987 77 989 999 999 999 999 999 999 889 888 888 888 888 888 888 888 899 ok

7.

݌݋ݑݎ ݊ ≥ 6

ሺ8. 10௡ିଵ+ ሺ10௡ିହ− 1ሻ. 10+ 8877ሻ൬9. 10௡ିଵ+8

9 ሺ10௡ିଶ− 1ሻ. 10 + 7൰= 88. 10ଶ௡ିଶ+ ሺ10௡ି଺− 1ሻ. 10௡ାଶ+ 888. 10௡ିଵ+7

9 ሺ10௡ିଷ− 1ሻ. 10+ 9899

6 898 877 988 887 888 887 779 899 ok

7 8 998 877 9 888 887 88 988 877 779 899 ok

8 89 998 877 98 888 887 8 899 888 777 779 899 ok

9 899 998 877 988 888 887 889 998 887 777 779 899 ok

10 8 999 998 877 9 888 888 887 88 999 988 877 777 779 899 ok

11 89 999 998 877 98 888 888 887 8 899 999 888 777 777 779 899 ok

12 899 999 998 877 988 888 888 887 889 999 998 887 777 777 779 899 ok

13 8 999 999 998 877 9 888 888 888 887 88 999 999 988 877 777 777 779 899 ok

14 89 999 999 998 877 98 888 888 888 887 8 899 999 999 888 777 777 777 779 899 ok

15 899 999 999 998 877 988 888 888 888 887 889 999 999 998 887 777 777 777 779 899 ok

16 8 999 999 999 998 877 9 888 888 888 888 887 88 999 999 999 988 877 777 777 777 779 899 ok

17 89 999 999 999 998 877 98 888 888 888 888 887 8 899 999 999 999 888 777 777 777 777 779 899 ok 18 899 999 999 999 998 877 988 888 888 888 888 887 889 999 999 999 998 887 777 777 777 777 779 899 ok 19 8 999 999 999 999 998 877 9 888 888 888 888 888 887 88 999 999 999 999 988 877 777 777 777 777 779 899 ok 20 89 999 999 999 999 998 877 98 888 888 888 888 888 887 8 899 999 999 999 999 888 777 777 777 777 777 779 899 ok 21 899 999 999 999 999 998 877 988 888 888 888 888 888 887 889 999 999 999 999 998 887 777 777 777 777 777 779 899 ok 22 8 999 999 999 999 999 998 877 9 888 888 888 888 888 888 887 88 999 999 999 999 999 988 877 777 777 777 777 777 779 899 ok 23 89 999 999 999 999 999 998 877 98 888 888 888 888 888 888 887 8 899 999 999 999 999 999 888 777 777 777 777 777 777 779 899 ok 24 899 999 999 999 999 999 998 877 988 888 888 888 888 888 888 887 889 999 999 999 999 999 998 887 777 777 777 777 777 777 779 899 ok 25 8 999 999 999 999 999 999 998 877 9 888 888 888 888 888 888 888 887 88 999 999 999 999 999 999 988 877 777 777 777 777 777 777 779 899 ok

(5)

8. Un huitième et un neuvième, pour lesquels nous n’avons pas trouvé de formulation mathématique simple, mais testés jusqu’à ݊ = 10 000

3 877 887 777 899 ok

4 7 877 9 887 77 879 899 ok

5 77 877 99 887 7 778 899 899 ok

6 877 877 999 887 877 777 799 899 ok

7 7 877 877 9 999 887 78 777 879 799 899 ok

8 77 877 877 99 999 887 7 787 778 899 799 899 ok

9 877 877 877 999 999 887 877 877 777 799 799 899 ok

10 7 877 877 877 9 999 999 887 78 778 777 879 799 799 899 ok

11 77 877 877 877 99 999 999 887 7 787 787 778 899 799 799 899 ok

12 877 877 877 877 999 999 999 887 877 877 877 777 799 799 799 899 ok

13 7 877 877 877 877 9 999 999 999 887 78 778 778 777 879 799 799 799 899 ok

14 77 877 877 877 877 99 999 999 999 887 7 787 787 787 778 899 799 799 799 899 ok

15 877 877 877 877 877 999 999 999 999 887 877 877 877 877 777 799 799 799 799 899 ok

16 7 877 877 877 877 877 9 999 999 999 999 887 78 778 778 778 777 879 799 799 799 799 899 ok

17 77 877 877 877 877 877 99 999 999 999 999 887 7 787 787 787 787 778 899 799 799 799 799 899 ok 18 877 877 877 877 877 877 999 999 999 999 999 887 877 877 877 877 877 777 799 799 799 799 799 899 ok 19 7 877 877 877 877 877 877 9 999 999 999 999 999 887 78 778 778 778 778 777 879 799 799 799 799 799 899 ok 20 77 877 877 877 877 877 877 99 999 999 999 999 999 887 7 787 787 787 787 787 778 899 799 799 799 799 799 899 ok 21 877 877 877 877 877 877 877 999 999 999 999 999 999 887 877 877 877 877 877 877 777 799 799 799 799 799 799 899 ok 22 7 877 877 877 877 877 877 877 9 999 999 999 999 999 999 887 78 778 778 778 778 778 777 879 799 799 799 799 799 799 899 ok 23 77 877 877 877 877 877 877 877 99 999 999 999 999 999 999 887 7 787 787 787 787 787 787 778 899 799 799 799 799 799 799 899 ok 24 877 877 877 877 877 877 877 877 999 999 999 999 999 999 999 887 877 877 877 877 877 877 877 777 799 799 799 799 799 799 799 899 ok 25 7 877 877 877 877 877 877 877 877 9 999 999 999 999 999 999 999 887 78 778 778 778 778 778 778 777 879 799 799 799 799 799 799 799 899 ok

3 887 877 777 899 ok

4 7 887 9 877 77 899 899 ok

5 87 887 99 877 8 777 889 899 ok

6 887 887 999 877 887 777 789 899 ok

7 7 887 887 9 999 877 78 877 899 789 899 ok

8 87 887 887 99 999 877 8 788 777 889 789 899 ok

9 887 887 887 999 999 877 887 887 777 789 789 899 ok

10 7 887 887 887 9 999 999 877 78 878 877 899 789 789 899 ok

11 87 887 887 887 99 999 999 877 8 788 788 777 889 789 789 899 ok

12 887 887 887 887 999 999 999 877 887 887 887 777 789 789 789 899 ok

13 7 887 887 887 887 9 999 999 999 877 78 878 878 877 899 789 789 789 899 ok

14 87 887 887 887 887 99 999 999 999 877 8 788 788 788 777 889 789 789 789 899 ok

15 887 887 887 887 887 999 999 999 999 877 887 887 887 887 777 789 789 789 789 899 ok

16 7 887 887 887 887 887 9 999 999 999 999 877 78 878 878 878 877 899 789 789 789 789 899 ok

17 87 887 887 887 887 887 99 999 999 999 999 877 8 788 788 788 788 777 889 789 789 789 789 899 ok 18 887 887 887 887 887 887 999 999 999 999 999 877 887 887 887 887 887 777 789 789 789 789 789 899 ok 19 7 887 887 887 887 887 887 9 999 999 999 999 999 877 78 878 878 878 878 877 899 789 789 789 789 789 899 ok 20 87 887 887 887 887 887 887 99 999 999 999 999 999 877 8 788 788 788 788 788 777 889 789 789 789 789 789 899 ok 21 887 887 887 887 887 887 887 999 999 999 999 999 999 877 887 887 887 887 887 887 777 789 789 789 789 789 789 899 ok 22 7 887 887 887 887 887 887 887 9 999 999 999 999 999 999 877 78 878 878 878 878 878 877 899 789 789 789 789 789 789 899 ok 23 87 887 887 887 887 887 887 887 99 999 999 999 999 999 999 877 8 788 788 788 788 788 788 777 889 789 789 789 789 789 789 899 ok 24 887 887 887 887 887 887 887 887 999 999 999 999 999 999 999 877 887 887 887 887 887 887 887 777 789 789 789 789 789 789 789 899 ok 25 7 887 887 887 887 887 887 887 887 9 999 999 999 999 999 999 999 877 78 878 878 878 878 878 878 877 899 789 789 789 789 789 789 789 899 ok

9. Récapitulatif

ܽ

ܾ

ܿ

8. 10௡ିଵ+7

9 ሺ10௡ିଵ− 1ሻ 8. 10௡ିଵ+ ሺ10௡ିଷ− 1ሻ. 10+ 87

78. 10

ଶ௡ିଶ

+ ሺ10

௡ିସ

− 1ሻ10

௡ାଶ

+ 87.10

+ 8

9 ሺ10

௡ିଶ

− 1ሻ10

+ 99 8877 8887 10

ସ௡ିଵ

− 1

10

− 1 7 889. 10

ସ௡

+ 7 788 10

ସሺ௡ିଶሻ

− 1

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+ 77 879 899

8

9 ሺ10− 1ሻ. 10 + 7 ሺ10௡ିଷ− 1ሻ. 10+ 8877

8

9 ሺ10

௡ିଷ

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௡ାହ

+ 7888. 10

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9 ሺ10

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89 ሺ10௡ିସ− 1ሻ. 10+ 7987 ሺ10௡ିଷ− 1ሻ. 10+ 777

8

9 ሺ10

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+ 7

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9 ሺ10௡ିଶ− 1ሻ. 10+ 77 ሺ10௡ି଺− 1ሻ. 10+ 898887

8

9 ሺ10

௡ି଺

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௡ା଺

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9 ሺ10

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78. 10௡ିଶ+7

9 ሺ10௡ିଶ− 1ሻ 98. 10௡ିଶ+ ሺ10௡ିସ− 1ሻ. 10+ 87 7798. 10ଶ௡ିସ+ ሺ10௡ି଺− 1ሻ. 10௡ାଶ+ 889.10௡ିଵ+8

9 ሺ10௡ିଷ− 1ሻ. 10+ 99 8. 10௡ିଵ+ ሺ10௡ିହ− 1ሻ. 10+ 8877 9. 10௡ିଵ+8

9 ሺ10௡ିଶ− 1ሻ. 10 + 7 88. 10ଶ௡ିଶ+ ሺ10௡ି଺− 1ሻ. 10௡ାଶ+ 888. 10௡ିଵ+7

9 ሺ10௡ିଷ− 1ሻ. 10+ 9899

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