Question

what is the mystery of 3 6 and 9

Answer 1

0 × 9 + 1 = 1 
1 × 9 + 2 = 11 
12 × 9 + 3 = 111 
123 × 9 + 4 = 1111 
1234 × 9 + 5 = 11111 
and so on 

9 × 9 + 7 = 88 
9 × 98 + 6 = 888 
9 × 987 + 5 = 8888 
9 × 9876 + 4 = 88888 
and so on. 

9² = 81 
99² = 9801 
999² = 998001 
9999² = 99980001 
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