50
575 is halfway between 550 and 600.
550 is halfway between 500 and 600
The halfway point between 500 and 600 is (500 + 600) ÷ 2 = 550
The year 550, as with any year between 501 and 600, fell in the sixth century.
550 to 600 is an increase not a decrease. Anyway, the amount of the increase is 9.09091%. If you go from 600 to 550 it is an 8.33% decrease.
How about: 550
550-600 years maybe
600
600
600
600