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The last evaluates to:
Second (Quantity[52560000, (“Megabits”)/(“Seconds”)])
Why is there a Megabits / Seconds and Second as an result. I would expect that Convert[Month, Second] should evaluate to something which is a number of Seconds.
You’re mixing two packages, the built-in functionality and the one from (the very old) Units. Try not to use the Units package any more, everything is now built-in, use the functions:
UnitConvert (*also to 'simplify' *)
Quantity
QuantityMagnitude