Numerology is a common source of online misinformation and unreliable memes. The belief that certain numbers or numerical patterns hold mystical powers has been involved in conspiracy theories about terrorist attacks, hurricanes and World War II leaders.
Equally, internet users often spread much more trivial and less sinister claims about hidden numerical patterns and coincidences.
In September 2018, an old and recurring example of this phenomenon gained popularity on Facebook, Instagram and Twitter, with images claiming that "Only today your age + year of birth. The total will be 2018. This only happens every 1000 years":
Most readers who performed this calculation will have found it to be true. The reason for this is not some mysterious, once-a-millennium event, but rather simple mathematics.
If I am 18 years old and I was born in the year 2000, adding 18 and 2,000 will yield 2,018. Equally, if I am 40 years old and I was born in the year 1978, adding 40 to 1,978 will also give me 2,018.
The "trick," such as it is, only works if your birthday has already taken place in 2018. In October 2018, someone born in November 2000 is still only 17 years old, just as someone born in November 1978 is still 39 years old -- in both cases the calculation yields a total of 2,017 rather than 2,018.
In logical terms, the reason this meme sometimes tricks people into believing they have witnessed something incredible or meaningful is that it expresses your age and your birth year as two separate facts, rather than explaining (as we all actually know) that your age is a function of your birth year. You are the age you are because your age is the number of full years that have passed since you were born.
The "age + birth year" canard is an old one. Internet users spread an almost identical meme in 2017:
Strange but true! But how? pic.twitter.com/rZTY1L1EF9
— Rishi Kapoor (@chintskap) July 16, 2017