# Lifespan puzzle

Sue and Thomas both lived for 17916 days, although they were born in different years in the same calendar (the modern Gregorian one). Thomas was 2 days older than Sue when he died. How can this be?

Sue was 49 years and 18 days old when she died Thomas was 49 years and 20 days old when he died

17916 days
365*49 is 17885, plus 18 to 20 is 17903 to 17905
plus 13 or 11 leap-years is 17916 or 17916

• Sue was born in October 1935, Thomas was born in January 1886 1900 was not a leap year, so Sue lived through 13 leap years while Thomas, born in 1886, lived through only 11. Feb 22, 2017 at 14:40
• Yea, i wanted to add something like that now. I know that 1700,1800 and 1900 wasn't leap years, but 1600 or 2000 were. Feb 22, 2017 at 17:13

Well, because of

leap years

it is possible for two people to

live the same number of days, but different numbers of (years + leftover days).

In particular,

if Sue was born on 1848-01-01 and Thomas on 1852-03-01 then the numbers are as in the puzzle.

But

I wouldn't say that one is "2 days older" than the other in this case. They are the same number of days old.

• They are the same age, but people conventionally measure their age in terms of years, which are not all the same length. Has they both lived a bit longer Thomas might have celebrated his 50th birthday and Sue missed out on hers a day "later". Feb 22, 2017 at 14:43

Leap years or other calendar oddities play no part except at the end. The puzzle states that they both lived exactly 17916 days. It further states that he was two days older than her when he died. That means that he was born two days before her and was always two days older. There is no other possibility. Look again at the text it says that they lived the same number of days, but no where does it say that they were born on the same day. The final condition is that they were born in different years. He could have been born on December 31, and she was born January 2. So when he died he was two days older than her and she would have to die two days later.

• Simple and straight thinking. Other answers show why we unnecessarily complicate things in life. :) May 11, 2017 at 13:31

Well, ...

Let's say they counted a year as

exactly the time the earth needs to revolve around the sun

then the explaination with the

leap years

doesn't work.

Since we don't have any clue in what time this story plays we could assume

That Sue and Thomas are people living in the future (2217 or so).

Sue is

an astronaut travelling at a very high speed (> 0.1c)

Thomas stays

on earth

When Sue

travels back to earth, time on earth has actually gone faster (so that Thomas may be 2 days older) (because of special relativity, see below)

but they lived the exactly same amount of

"earth days".

This effect is called

Time dilation and can actually be measured with today's technology.