Puzzle/Problem No. 1

Let me start with a simple mathematics question.
What is the significance of the number "2519"? The answer is:
This is the smallest number which when divided by 10 leaves a remainder of 9
when divided by 9 gives a remainder of 8, when divided by 8 gives a remainder of 7,
When divided by 7 leaves 6 as remainder, when divided by 6 leaves 5 as remainder,
when divided by 5 leaves 4 as remainder, when divided by 4 leaves 3 as remainder,
when divided by 3 leaves 2 as remainder and when when divided by 2 leaves 1 as remainder.
Interesting! is n't it? Now the question is how do you arrive at the number?
Pl. try your self and if not successful wait for my next blog where I will give answer.