Keunikan Angka Matematika

Sebenarnya ini hanya permainan angka yang unik. Coba lihat piramida angka dibawah ini:

1 x 8 + 1 = 9
12 x 8 + 2 = 98
123 x 8 + 3 = 987
1234 x 8 + 4 = 9876
12345 x 8 + 5 = 98765
123456 x 8 + 6 = 987654
1234567 x 8 + 7 = 9876543
12345678 x 8 + 8 = 98765432
123456789 x 8 + 9 = 987654321

1 x 9 + 2 = 11
12 x 9 + 3 = 111
123 x 9 + 4 = 1111
1234 x 9 + 5 = 11111
12345 x 9 + 6 = 111111
123456 x 9 + 7 = 1111111
1234567 x 9 + 8 = 11111111
12345678 x 9 + 9 = 111111111
123456789 x 9 +10= 1111111111

9 x 9 + 7 = 88
98 x 9 + 6 = 888
987 x 9 + 5 = 8888
9876 x 9 + 4 = 88888
98765 x 9 + 3 = 888888
987654 x 9 + 2 = 8888888
9876543 x 9 + 1 = 88888888
98765432 x 9 + 0 = 888888888

Kemudian, lihat juga piramida perkalian ini:

1 x 1 = 1
11 x 11 = 121
111 x 111 = 12321
1111 x 1111 = 1234321
11111 x 11111 = 123454321
111111 x 111111 = 12345654321
1111111 x 1111111 = 1234567654321
11111111 x 11111111 = 123456787654321
111111111 x 111111111 = 12345678987654321

Sekarang, mari kita lihat keunikan angka 9

9 x 1 = 09 (0 + 9 = 9)
9 x 2 = 18 (1 + 8 = 9)
9 x 3 = 27 (2 + 7 = 9)
9 x 4 = 36 (3 + 6 = 9)
9 x 5 = 45 (4 + 5 = 9)
9 x 6 = 54 (5+ 6 = 9)
9 x 7 = 63 (6 + 3 = 9)
9 x 8 = 72 (7 + 2 = 9)
9 x 9 = 81 ( 8 + 1 = 9)
9 x 10 = 90 (9 + 0 = 9)

sumber: http://matikclub.wordpress.com/2011/10/22/keunikan-angka-matematika-2/