The answer is 25.5 (twenty five point five).
Half of 51/57 = 51/(57*2) = 51/114 = 0.4474 approx.
.51
51
51 and a half
51/2
Chromium-51 has a half-life of 27.7 days, and is thus fairly active.
25
Half of 103 (103 divided by 2) is 51.5 or 51 1/2.
51 seconds
280.5
Half of 120 would be 60
Anything from 51% to 74%.