Calculating the Mass Defect of 40Ca

[Intrusionv2]

Homework Statement

What is the mass defect of the 40Ca nucleus?

Homework Equations

Δm=(Zmp+(A-Z)mn)-m

The Attempt at a Solution

mass of 40Ca=40.078 amu
mass of proton in amu is mp=1.0073 amu
mass of neutron is mn=1.0087 amu
atmomic number of 40Ca is Z=20
its mass number is A=40
so the mass defect is
Δm=(Zmp+(A-Z)mn)-m
=0.242 amu

But it says the correct answer is 0.367u, why? What am I doing wrong? Thanks.

 

[MednataMiza]

Δm=(Zmp+(A-Z)mn)-(m-Zme)
Now the formula looks better :)

 

[Intrusionv2]

Nvm, got it, thanks