Is there a fast way to solve this system of congruences on paper?
x = 9 (mod 10)
x = 8 (mod 9)
x = 7 (mod 8)
x = 6 (mod 7)
x = 5 (mod 6)
x = 4 (mod 5)
x = 3 (mod 4)
x = 2 (mod 3)
x = 1 (mod 2)
This is part of a homework word problem from my class. I don't think the Chinese remainder theorem works since the modulo are not pairwise relatively prime. The only way I can think of solving it would take 30 minutes at least without a computer. So I'm wondering if there is a better way.
edit: I proved this must be one less than the least common multiple, i.e.
2519 (mod 2520)