How do you find the number of neutrons in an element on the periodic table?

Explanation:
The atomic number represents the number of protons in an element and is on top of the symbol for that element ... this is always a whole number.
Right below the chemical symbol, you will find a number that usually has decimals and is not a whole number...this is the atomic mass of the element, and it represents the number of protons and neutrons in the element, the reason why it does not also account for the electrons is because the electron mass is negligible....
So right now, you have two things: the number of protons in the element, and the combined number of protons and neutrons in that element...so how would you find just the number of neutrons.
Rounded Atomic Mass to the whole number - the Atomic Number= Number of Neutrons of the element