Miscalculation

noun

1. Erroneous calculation or estimate.
2. a mistake in calculating.
3. An error in judgment, especially about the effects of action or the likely course of events.

   "IBM's miscalculation about the impact of microcomputers cost them many billions in lost opportunities; Sadam's invasion of Kuwait was only his worst, but not his last, miscalculation"

4. An incorrect or mistaken calculation
5. a mistake in calculating