Posted by Anonymous...urgent! on Monday, March 4, 2013 at 12:24am.
How many 7 digit positive integers are there such that the product of the individual digits of each number is equal to 10000?

GEOmetry  Steve, Monday, March 4, 2013 at 4:46am
10000 = 10^4 = 2^4 * 5^4
so, the digits must be all 1's, 2's and 5's
Since you need all 8 2's and 5's to get 10,000, no 7digit number will do it. 
GEOmetry  Devin, Wednesday, March 6, 2013 at 8:51am
4455551 = 4x4x5x5x5x5x1=10000
the proof is not valid.