Well that is the explanation peet. If any whole number expression involving parts that are under the size of an int are used, VB will treat them as ints, and try to force the result into an int as well. Putting type declaration chars on values you suspect may go over the boundaries will prevent it though.
VB Code:
  1. 'in debug window

  2. ?6000*10 'error

  3. ?6000&*10&

  4.  60000