The total number of protons and neutrons in an atom is called the mass number. You can find the mass numberfor any element. The mass number canbe found by rounding the average atomic mass to the nearest whole number. as an example 6.25 is closer to 6 than 7 so it is 6 6. 50 is closer to 7 so it is 7 you have to look at the thenth digit. if the number is 4 or less you have to round it down if the tenth digit is 5 or greather than you have to round it up.
