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A productive s.o.d. (Posted on 2012-09-19) Difficulty: 3 of 5
Let us denote f(n) = 12...12 (repeated n times) and g(n) = 3...3 (repeated n times). For example: f(3) = 121212 and, g(3) = 333.

(i) Determine the distinct digits in the base ten expansion of f(n)*g(n) whenever n ≥ 3

(ii) Express s.o.d (f(n)*g(n)) in terms of n

*** s.o.d (x) denotes the sum of digits in the base ten expansion of x

No Solution Yet Submitted by K Sengupta    
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re: A start | Comment 3 of 5 |
(In reply to A start by Jer)

.....We could start by writing formulas for f and g"...

and in the definition f should be g and vice versa.

-JUST FOR THE RECORD. - ...Please edit

  Posted by Ady TZIDON on 2012-09-19 21:43:56
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