The square and round brackets denote closed and open intervals. A closed interval includes the number, and open interval excludes it. So 79.99999 gets grade C , but 80 gets grade B.
Special note: The algorithm can give a date in April. Also, if the year is one of four special years (1954, 1981, 2049, or 2076) then subtract 7 from the date.
year = int(input("Please enter a year"))
if year >= 1900 and year <= 2099:
a = year % 19
b = year % 4
c = year % 7
d = (19*a + 24) % 30
e = (2*b + 4*c + 6*d + 5) % 7
dateofeaster = 22 + d + e
if year == 1954 or year == 2981 or year == 2049 or year == 2076:
dateofeaster = dateofeaster - 7
if dateofeaster > 31:
print("April", dateofeaster - 31)
else:
print("March", dateofeaster)
else:
print("ERROR...year out of range")