My answer is
n=2 : 140
n=3 : 1400
n=4 : 14000


Edited by author 23.12.2005 20:41

You can find answer for n=2 yourself with bruteforce solution. And it's not 140. :)

Good luck!

I solve this problem:

 n=1 -> write(14)
 n=2 -> write(155)
 n=3 -> write(1575)
 n=4 -> write(15750)
 n=5 -> write(157500)
 .................
 n=m -> write(157500...00) (n-3 zeros)

Edited by author 24.12.2005 07:42

Edited by author 24.12.2005 07:43

Угу... счас! WA#7!
Хотя моя программа выдаёт те же самые числа до n = 5 включительно, дальше считать не стал, ибо придётся загнать комп до чёрного дыма >___<"

Poleshuk_N is right. Try to solve this as a mathematical problem! Here are some ideas for you.

Let "m=a*10^n+b".
'a' divides 'm', hence 'a' divides "b=m-a*10^n", too. Let "b=k*a", where 'k' is a natural number (it cannot be zero as 'b' cannot be zero). Moreover, "k<10" (obvious).
On the other hand, 'b' divides 'm', hence 'b' divides "a*10^n=m-b", too. This means that "(a*10^n)/b=(a*10^n)/(k*a)=(10^n)/k" is integer. Thus 'k' is a divisor of '10^n': 1,2,4,5 or 8.
But don't forget two special cases:
1) if "n=1", 'k' may be one of: 1,2,5;
2) if "n=2", 'k' may be one of: 1,2,4,5.
Then you can perform some simple calculations and find out the answer.

Edited by author 07.08.2011 05:12