How many seconds are there in one year. I come up with 31557600 sec.

There are 3600 seconds in 1 hour.

24 hours in a day.

365 days in a year.

3600*24*365=31,536,000 seconds in 1 year.

You could even figure a year to be 365.25 to allow for the leap year.
Which could be 3600x24x365.25=31,557,600