It is really easy if you look up an electron configuration table (one that looks like a periodic table) and then just go down the rows left to right, top to bottom, and just stop when you get to where the element is on the table.
The 32.06 represent The atomic mass, the average number of protons & neutrons
<h3>Further explanation
</h3>
The Atomic Number (Z) indicates the number of protons in an atom of an element. If the atom is neutral then the number of protons will be equal to the number of electrons. So the atomic number can also indicate the number of electrons.
So atomic number = number of protons = number of electrons
Mass Number (A) is the sum of protons and neutrons
Mass Number (A) = Number of protons + Number of Neutrons
So that the relationship between atomic numbers and mass numbers can be formulated as follows:
Atomic Number (Z) = Mass Number (A) - Number of Neutrons
In the following element notation,

X = symbol of elemental atom
A = mass number
= number of protons + number of neutrons
Z = atomic number
= number of protons = number of electrons, on neutral elements
Explanation:
Atomic Number = Number of protons
Mass Number = Number of protons + Number of neutrons
Isotopes are simply atoms of an element with the same number of protons and different number of neutrons.
First Isotope -- 238U
Number of neutrons = Mass Number - Atomic Number
Number of neutrons = 238 - 92 = 146
Second Isotope -- 235U
Number of neutrons = Mass Number - Atomic Number
Number of neutrons = 235 - 92 = 143