keunikan matematika

1 x8 +1 =9
12 x8 +2 =98
123 x8 +3 =987
1234 x8 +4 =9876
12345 x8 +5 =98765
123456 x8 +6 =987654
1234567 x8 +7 =9876543
12345678 x8 +8=98765432
123456789 x8 +9=987654321

9 x9 +7 =88
98 x9 +6 =888
987 x9 +5 =8888
9876 x9 +4 =88888
98765 x9 +3 =888888
987654 x9 +2 =8888888
9876543 x9 +1 =88888888
98765432 x9 +0 =888888888