You can recycle your old calendars by using them again!


Here are all years 1900 through 2100. Every row contains years which share a calendar:
1900 1906 1917 1923 1934 1945 1951 1962 1973 1979 1990 2001 2007 2018 2029 2035 2046 2057 2063 2074 2085 2091
1901 1907 1918 1929 1935 1946 1957 1963 1974 1985 1991 2002 2013 2019 2030 2041 2047 2058 2069 2075 2086 2097
1902 1913 1919 1930 1941 1947 1958 1969 1975 1986 1997 2003 2014 2025 2031 2042 2053 2059 2070 2081 2087 2098
1903 1914 1925 1931 1942 1953 1959 1970 1981 1987 1998 2009 2015 2026 2037 2043 2054 2065 2071 2082 2093 2099
1904 1932 1960 1988 2016 2044 2072
1905 1911 1922 1933 1939 1950 1961 1967 1978 1989 1995 2006 2017 2023 2034 2045 2051 2062 2073 2079 2090
1908 1936 1964 1992 2020 2048 2076
1909 1915 1926 1937 1943 1954 1965 1971 1982 1993 1999 2010 2021 2027 2038 2049 2055 2066 2077 2083 2094 2100
1910 1921 1927 1938 1949 1955 1966 1977 1983 1994 2005 2011 2022 2033 2039 2050 2061 2067 2078 2089 2095
1912 1940 1968 1996 2024 2052 2080
1916 1944 1972 2000 2028 2056 2084
1920 1948 1976 2004 2032 2060 2088
1924 1952 1980 2008 2036 2064 2092
1928 1956 1984 2012 2040 2068 2096

I got the idea for this while watching the Simpsons.
When Marge wanted Homer to throw out some old calendars he replied,

Sure, it's not 1985 now, but who knows what tomorrow will bring?




And then I thought, "well wait a minute, those calendars might actually work again some day."