Find the change in mass from the KE (nuclear decay)

[Blanchdog]

Homework Statement

A nucleus A decays into two nuclei B and C. The two nuclei have a combined kinetic energy of 581.9 MeV. What is the difference between the rest mass of the parent nucleus A and the combined rest mass of the two produced nuclei? Give your answer in atomic mass units u, with 5 decimals.

Homework Equations

Δmc² = KE_B + KE_C
1 u = 931.5 MeV/c^2

The Attempt at a Solution

Δm = KE (Total given in problem statement) / c² * c² / 931.5 MeV
Δm = .62469 u

This is incorrect the correct answer is .62319 u

Close but not quite; what am I missing?

 

[mfb]

You should use the atomic mass unit with at least 5 digits if the answer asks for 5 digits, better 6 or even 7.
.62469 u is much closer to the right answer than .62319 u, however, and I don't see an obvious way how to arrive at the wrong answer. The old chemistry/physics definitions of the atomic unit are too close to explain the difference, and there is no single-digit typo that would lead to the wrong answer.