I need to Calculate which part of the total mass of atom Fe 56 responsible
1)Neutron
2)proton
3)electron
I know that in this atom there 26 proton and electron and 30 Neutron
But how can I know the mass of everyone of them

May I need to use in this Formula for proton:26*1.672×10-27
And the same with electron and Neutron (sure everyone of them have his own Formula )

Thanks :)

Yes, that's right.

OK so I tried to do like this to Calculate the mass of proton here and I did:26*1.673*10^-27
and the answer need to be 0.4639
what I do wrong ?
thanks.

You calculated the mass correctly. However, the question didn't ask what was the mass. It asked what fraction of the total mass was contributed by each.

Correct now I see it.

Thanks.