Arduino can't multiply?
2500 * 1000 = 9632 is exactly what you expect with 16-bit integers. You
should use long integers instead:

2500L * 1000L == 2500000L


Floats work also, but are more expensive:

2500.0 * 1000.0 == 2500000.0


although I do not recommend testing for exact equality of floats (it
works here because these numbers are exactly representable).