A lecturer in algebra at ANU told AAP FactCheck “if you add your age to your birth year, you will ‘always’ get the current year”.

Age and birth year claim doesn’t occur every 1000 years

FactCheck October 7, 2019

The Statement

AAP FactCheck examined a Facebook post from September 24, 2019 by an Australian user which features a claim that if a person adds their age to the year they were born, it would equal 2019, and that this only happens every 1000 years.

A Facebook post from September 24, 2019, claims that if a person adds their age to their birth year, it would equal 2019, and that this only happens every 1000 years.

 The post’s full text reads, “All the people in the world are of the same age this year! It’s amazing: this year is special. It happens only once every 1,000 years. This year your age + your year of birth, every individual is = 2019. For example, you are 55 years old and you were born in 1964, which adds up to 2019. Very strange, even the Chinese and foreign masters can not explain. Please calculate and see if the answer is 2019. It’s a thousand-year wait! Good shot! Go to the circle of friends, let everybody calculate it!”

The post has been shared more than 2500 times and attracted more than 70 comments and 230 reactions. 

The Analysis

The age and year of birth post has been circulating on social media since at least 2017, and the key to this claim is simple mathematics. 

Dr Anand Deopurkar, a lecturer in algebra and research fellow at the Australian National University’s College of Science, told AAP FactCheck via email thatif you add your age to your birth year, you will ‘always’ get the current year”. 

“This happens no matter what the current year is, and therefore, is nothing special to 2019,” he said. “In particular, this does not happen ‘only once every 1000 years’.”

Dr Deopurkar provided an example. “Let us suppose, hypothetically, that we are doing this exercise next year (2020), and use my birth year (1986). My age is, by definition, the number of years passed since my birth, which will be (2020 – 1986 = 34) in year 2020.”

“When you add my age to my birth year, you are doing: 1986 + 34 = 2020, which is the current year.”

Dr Katharine Turner, a researcher in computational mathematics and algebra and topology at the ANU’s Mathematical Sciences Institute, told AAP FactCheck: “What is true is that from your birthday in 2019 until your birthday in 2020 your (age + birth year) will equal 2019. 

“More generally from your birthday in year X until your birthday in year X+1, your (age + birth year) will equal X.  The ‘thousand-year wait’ claim is a bit misleading as it never happened before and never will again.”

The Verdict

Based on the evidence, AAP FactCheck found the Facebook post to be false. Adding your age to the year you were born will always result in the current year, according to two academics. This occurs every year, not every 1000 years as the post claims. 

False – The primary claim of the content is factually inaccurate.

First published October 7, 2019, 13:18 AEST

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