Re: Math problem: help

[Pham Thi Thanh Hong <smm68490@ait.ac.th>]

 On Sun, 16 Mar 1997, Tuan V Nguyen wrote:
 
 > Hello math folks,
 > 
 >         My son has a math problem, which I can not figure 
 > out yet, and I would be grateful for your help. The problem 
 > is: 
 > 
 > "Find the largest seven-digit number (say X), where X is 
 > divisible to every digit. Note that the seven digits are 
 > unique (no repetition.)"
 > 
 > 
 > 	Thank you in advance for your help.
 > 
 > 	Tuan 
 > 
 > 
 > 
 > 
 
 Hi Tuan, & Trung
 
 Sorry for a wrong previous solution. This number is undivisable for 8. I
have tried another way to get solution as follows:
 
 ---------------
 Solution
 
Because, it is the largest seven - digit number and those digits are
unique, so I can guest it is formed under a down trend as 9876543.
 
Firstly, we have to find a smalleast number that is divisable for every
digit. This must be 2520.

The maximum number that is divisable for 2520 under 9876543 is 9875880.
Because this number consists of triple 8, therefore, we must to find
another one which under this value. 

By subtracting the amount of 2520 from the number of 9875880 till every
digit of X is different each other, we get the result of 9843120.  

Thus, the expected number must be 9843120.
 
Test it again, OK.

H