@Sid Mass of nucleon means mass of one proton or neutron.
$$\text{No of nucleons} = \frac{\text{mass of one atom} }{\text{Mass of one nucleon}}$$
Now, I have confusion in this formula that why is it division. Mass of an atom = mass of electron + mass of proton + neutron. [![enter image description here][1]][1]Now, I am not exactly sure if this is right. Please correct me here.
It’s like in a bag there are 4 apples and 3 mango and 2 orange. Total = 9 fruits.
Then, total number of oranges are not equal to 9 / 2.