There are 60 seconds in a minute, 60 minutes in an hour, and 24 hours in a day. There are, therefore, 60x60x24 = 86,400 seconds in a day.
There are about 2 years left out of a total of 13,023 years for all of history.
So we now define two ratios which must equal one another. One is years left to total years, and the other is seconds left (which we’ll call x) to seconds in a day. The two ratios, therefore, are:
x:86400 and 2:13023
Let’s rewrite these as fractions so that we can do math operations on them:
x 2 ----- = ----- 86400 13023
Now let’s cross-multiply in order to isolate x:
2x86400 x = ------- 13023
This simplifies to:
172800 x = ------ 13023
Which finally simplifies to:
x = 13.27
The number 13.27 is close enough to 13.25, so we can safely say, in simple language, that there are the equivalent of 13 and a quarter seconds left.