Issued as a cumulative or non-cumulative L/C, the former allows for unused credit amounts to rollover into subsequent periods while the latter maintains a fixed amount of credit available each period.
average atomic mass of magnesium is 24.3 g/mole so 24.3 X 1.56 X1021 / 6.02 X1023 = .063 grams.
The researchers found an isotope of magnesium with 28 neutrons (magnesium-40) â more than twice its normal complement. That's bigger than the previous heaviest magnesium isotope found, which had 26 neutrons. There doesn't seem to be a version of magnesium with 27 neutrons.